1 | In The Interpretation of Dreams, Freud implies that one dreamer’s homosexual desire was repressed—resulting in loneliness—rather than sublimated—which might have resulted in friendship:

I will analyse two dreams of this kind, one of which is also a ‘flying dream.’ They were both dreamt by the same person, a young man with strong homosexual leanings, which were, however, inhibited in real life.

He was attending a performance of ‘Fidelio’ and was sitting in the stalls at the Opera besides L., a man who was congenial to him and with whom he would have liked to make friends. Suddenly he flew through the air right across the stalls, put his hand in his mouth and pulled out two of his teeth.

He himself said of the flight that it was as though he was being ‘thrown’ into the air. Since it was a performance of Fidelio, the words:

Wer ein holdes Weib errungen …

might have seemed appropriate. But the gaining of even the loveliest woman was not among the dreamer’s wishes. Two other lines were more to the point:

Wem der grosse Wurf gelungen, Eines Freundes Freund zu sein …

The dream in fact contained this ‘great throw’, which, however, was not only a wish-fulfilment. It also concealed the painful reflection that the dreamer had often been unlucky in his attempts at friendship, and had been ‘thrown out’. It concealed, too, his fear that this misfortune might be repeated in relation to the young man by whose side he was enjoying the performance of Fidelio. And now followed what the fastidious dreamer regarded as a shameful confession: that once, after being rejected by one of his friends, he had masturbated twice in succession in the state of sensual excitement provoked by his desire.

Here is the second dream: He was being treated by two University professors of his acquaintance instead of by me. One of them was doing something to his penis. He was afraid of an operation. The other was pushing against his mouth with an iron rod, so that he lost one or two of his teeth. He was tied up with four silk cloths.

It can scarcely be doubted that this dream had a sexual meaning. The silk cloths identified him with a homosexual whom he knew. The dreamer had never carried out coitus and had never aimed at having sexual intercourse with men in real life; and he pictured sexual intercourse on the model of the pubertal masturbation with which he had once been familiar.

2 | Freud’s self-analysis, from the “Affect in Dreams” section of IoD:

My present-day anger, which was only slight, over the warning I had been given not to give anything away received reinforcements from sources in the depth of my mind and thus swelled into a current of hostile feelings against persons of whom I was in reality fond. The source of this reinforcement flowed from my childhood. I have already shown how my warm friendships as well as my enmities with contemporaries went back to my relations in childhood with a nephew who was a year my senior; how he was my superior, how I early learned to defend myself against him, how we were inseparable friends, and how, according to the testimony of our elders, we sometimes fought with each other and - made complaints to them about each other. All my friends have in a certain sense been reincarnations of this first figure who ‘früh sich einst dem trüben Blick gezeigt’: they have been revenants. My nephew himself re-appeared in my boyhood, and at that time we acted the parts of Caesar and Brutus together. My emotional life has always insisted that I should have an intimate friend and a hated enemy. I have always been able to provide myself afresh with both, and it has not infrequently happened that the ideal situation of childhood has been so completely reproduced that friend and enemy have come together in a single individual - though not, of course, both at once or with constant oscillations, as may have been the case in my early childhood. […]
But what had become of the dream-censorship? Why had it not raised the most energetic objections against this blatantly egoistic train of thought? And why had it not transformed the satisfaction attached to that train of thought into severe unpleasure? The explanation was, I think, that other, unobjectionable, trains of thought in connection with the same people found simultaneous satisfaction and screened with their affect the affect which arose from the forbidden infantile source. In another stratum of my thoughts, during the ceremonial unveiling of the memorial, I had reflected thus: ‘What a number of valued friends I have lost, some through death, some through a breach of our friendship! How fortunate that I have found a substitute for them and that I have gained one who means more to me than ever the others could, and that, at a time of life when new friendships cannot easily be formed, I shall never lose his!’ My satisfaction at having found a substitute for these lost friends could be allowed to enter the dream without interference; but there slipped in, along with it, the hostile satisfaction derived from the infantile source. It is no doubt true that infantile affection served to reinforce my contemporary and justified affection. But infantile hatred, too, succeeded in getting itself represented.

3 | In The Psychopathology of Everyday Life, Freud offers several personal examples where something was “forgotten” due to a strong negative association. In one example, he has forgotten the location of a safe shop as a result of a friendship gone sour:

I had undertaken to get a lady who was a stranger to Vienna a small strong-box for her documents and money. When I offered my services I had in my mind’s eye an unusually vivid picture of a shop-window in the Inner Town in which I was sure I had seen boxes of the kind. I could not, it was true, recall the name of the street, but I felt sure that I would find the shop if I walked through the town, since my memory told me I had passed it on countless occasions. To my chagrin I had no success in finding the shop-window with the strong-boxes, though I walked all over the Inner Town in every direction. I decided that the only course left was to look up the firms of safe-manufacturers in a trades directory, so as to be able to identify the shop on a second walk round the town. Such extreme measures, however, did not prove necessary; among the addresses given in the directory was one which I immediately recognized as the one I had forgotten. It was true that I had passed the shop- window innumerable times - every time, in fact, that I had visited the M. family, who have lived for many years in the same building. Our intimate friendship later gave place to a total estrangement; after that, I fell into the habit - the reasons for which I never considered - of also avoiding the neighbourhood and the house. On my walk through the town in search of the shop-window with the strong-boxes I had passed through every street in the district but this one, which I had avoided as if it were forbidden territory. The motive of unpleasure responsible in the present case for my failure to find my way is easy to recognize. The mechanism of forgetting, however, is not so simple here as in the preceding example. My aversion naturally applied not to the safe-manufacturer but to another person, whom I did not want to think about; and from this latter person it was then transferred to this occasion where it produced the forgetting.

4 | In Dora (Fragment of an Analysis of a Case of Hysteria), Dora meets Herr K only because her father had “formed an intimate friendship” with him and his wife. This is also the reason he does not believe his daughter’s claim that Herr K had tried to seduce her: “I am bound to Frau K. by ties of honourable friendship and I do not wish to cause her pain.” This is the case in which Freud is certain Dora is hysterical because, at 14, she has no sexual response to being forcibly kissed by her father’s friend:

In this scene - second in order of mention, but first in order of time - the behaviour of this child of fourteen was already entirely and completely hysterical. I should without question consider a person hysterical in whom an occasion for sexual excitement elicited feelings that were preponderantly or exclusively unpleasurable; and I should do so whether or no the person were capable of producing somatic symptoms. The elucidation of the mechanism of this reversal of affect is one of the most important and at the same time one of the most difficult problems in the psychology of the neuroses. In my own judgement I am still some way from having achieved this end; and I may add that within the limits of the present paper I shall be able to bring forward only a part of such knowledge on the subject as I do possess.

But Dora’s father and Frau K. are not really friends, as becomes clear, with Freud using the term only ironically:

During the first summer holidays after his recovery things had happened which must have opened everyone’s eyes to the true character of this ‘friendship’. The two families had taken a suite of rooms in common at the hotel.
Rather than (homosocial) friendship being the result of sublimated desire, later in Dora’s case, it looks like the main energy itself, which can successfully or unsuccessfully be redirected towards heterosexual aims:

It has long been known and often been pointed out that at the age of puberty boys and girls show clear signs, even in normal cases, of the existence of an affection for people of their own sex. A romantic and sentimental friendship with one of her school friends, accompanied by vows, kisses, promises of eternal correspondence, and all the sensibility of jealousy, is the common precursor of a girl’s first serious passion for a man. Thenceforward, in favourable circumstances, the homosexual current of feeling often runs completely dry. But if a girl is not happy in her love for a man, the current is often set flowing again by the libido in later years and is increased up to a greater or lesser degree of intensity.
This case falls apart—Dora is pulled from analysis before Freud makes the progress he hopes—because he refuses to help the father convince Dora that there is more than friendship between him and Frau K.

5 | In “Delusions and Dreams in Jensen's Gradiva,” Freud discusses repressed desire (for both friendship and sex) in a work of fiction:

With the young man, things had taken a different turn. Archaeology took hold of him and left him with an interest only in women of marble and bronze. His childhood friendship, instead of being strengthened into a passion, was dissolved, and his memories of it passed into such profound forgetfulness that he did not recognize or notice his early playmate when he met her in society.

[…]

Mathematics enjoys the greatest reputation as a diversion from sexuality. This had been the very advice to which Jean Jacques Rousseau was obliged to listen from a lady who was dissatisfied with him: ‘Lascia le donne e studia la matematica!’1 So too our fugitive threw himself with special eagerness into the mathematics and geometry which he was taught at school, till suddenly one day his powers of comprehension were paralysed in the face of some apparently innocent problems. It was possible to establish two of these problems : ‘Two bodies come together, one with a speed of … etc.’ and ‘On a cylinder, the diameter of whose surface is m, describe a cone … etc.’ Other people would certainly not have regarded these as very striking allusions to sexual events; but he felt that he had been betrayed by mathematics as well, and took flight from it too.

[…]

If Norbert Hanold were someone in real life who had in this way banished love and his childhood friendship with the help of archaeology, it would have been logical and according to rule that what revived in him the forgotten memory of the girl he had loved in his childhood should be precisely antique sculpture.

6 | In “On the Mechanism of Paranoia,” Freud theorizes why gay people often make important social contributions:

After the stage of heterosexual object-choice has been reached, the homosexual tendencies are not, as might be supposed, done away with or brought to a stop; they are merely deflected from their sexual aim and applied to fresh uses. They now combine with portions of the ego-instincts and, as ‘attached’ components, help to constitute the social instincts, thus contributing an erotic factor to friendship and comradeship, to esprit de corps and to the love of mankind in general. How large a contribution is in fact derived from erotic sources (with the sexual aim inhibited) could scarcely be guessed from the normal social relations of mankind. But it is not irrelevant to note that it is precisely manifest homosexuals, and among them again precisely those that set themselves against an indulgence in sensual acts, who are distinguished by taking a particularly active share in the general interests of humanity - interests which have themselves sprung from a sublimation of erotic instincts.

7 | From “The Dynamics of Transference”:

And we are thus led to the discovery that all the emotional relations of sympathy, friendship, trust, and the like, which can be turned to good account in our lives, are genetically linked with sexuality and have developed from purely sexual desires through a softening of their sexual aim, however pure and unsensual they may appear to our conscious self-perception.

8 | In Introductory Lectures, Freud describes the case of paranoid doctor who blames a childhood lover for all of his problems:

A young doctor had to be expelled from the town in which he lived because he had threatened the life of the son of a university professor residing there, who had up till then been his greatest friend. He attributed really fiendish intentions and demonic power to this former friend, whom he regarded as responsible for all the misfortunes that had befallen his family in recent years, for every piece of ill-luck whether in his home or in his social life. But that was not all. He believed that this bad friend and the friend’s father, the Professor, had caused the war, too, and brought the Russians into the country. His friend had forfeited his life a thousand times, and our patient was convinced that the criminal’s death would put an end to every evil. Yet his affection for him was still so strong that it had paralysed his hand when, on one occasion, he had an opportunity of shooting down his enemy at close range. In the course of the short conversations I had with the patient, it came to light that their friendship went back far into their schooldays. Once at least it had overstepped the bounds of friendship: a night which they had spent together had been an occasion for complete sexual intercourse. Our patient had never acquired the emotional relation to women which would have corresponded to his age and his attractive personality. He had once been engaged to a beautiful young girl of good social position; but she had broken off the engagement because she found that her fiancé was without any affection. Years later, his illness broke out just at the moment when he had succeeded for the first time in satisfying a woman completely. When this woman embraced him in gratitude and devotion, he suddenly had a mysterious pain that went round the top of his head like a sharp cut. Later on he interpreted this sensation as though an incision were being made at an autopsy for exposing the brain. And as his friend had become a pathological anatomist, it slowly dawned on him that he alone could have sent this last woman to him to seduce him- From that point onwards his eyes were opened to the other persecutions to which he believed he had been made a victim by the machinations of his one-time friend.