It sounds not only disagreeable but also paradoxical, yet it must nevertheless be said that anyone who is to be really happy in love must have surmounted his respect for women and have come to terms with the idea of incest with his mother or sister.
Sigmund Freud, “On the Universal Tendency to Debasement in the Sphere of Love,” 1912
In considering the question of abstinence, far too little distinction is made between two forms of it, namely, abstention from any kind of sexual activity at all, and abstention from heterosexual intercourse. Many who are proud of maintaining abstinence successfully have only been able to achieve it with the help of masturbation and other similar means of satisfaction, which are connected with the auto-erotic sexual activities of early childhood. But this very connection makes these substitutive measures of sexual satisfaction by no means harmless; they predispose to the numerous forms of neurosis and psychosis, which are conditional on a regression of the sexual life to its infantile form. Nor does masturbation at all correspond to the ideal demands of civilized sexual morality, and it therefore drives young people into the same conflicts with the ideals of education which they design to escape by abstinence. Further, the character is undermined in more ways than one by this indulgence; first, because it shows the way to attain important aims in an otiose manner, instead of by energetic effort, in line with the view that the attitude to sex is the prototype of the attitude to life; and secondly, because in the phantasies accompanying this gratification the sexual object is exalted to a degree which is seldom to be reproduced in reality. A witty writer, K. Kraus in the Vienna Fackel, has, as it were, expressed this truth paradoxically in the cynical saying: “Coitus is merely an unsatisfactory substitute for onanism!”
SigmundFreud, “Civilized’ Sexual Morality and Modern Nervousness” (1908)