In "On Aggression", published in 1963 by Konrad Lorenz, there's a description of sexual pairing in cichlid fish that's pure red pill theory. It's an interesting read.

Disclaimer: I don't endorse the generalization of cichlid behavior as absolute truth on human nature. It's just an interesting read.

Tl;dr: females need to fear to be aroused, males can't be aroused if they fear. That's how nature avoids homo pairings. Also, women shit-test more when they're horny.

The discovery that the lack of a certain behaviour pattern in the male and of another in the female was responsible for sex recognition in cichlids of opposite sexes entailed particularly acute observation. In these fish the relation of misceability of the three great drive sources is different in the male and in the female: in the male the motivations of flight and of sexuality cannot be mixed. If the male has even the slightest fear of his partner his sexuality is completely extinguished. In the female there is the same relation between aggression and sexuality: if she is so little in awe of her partner that her aggression is not entirely suppressed she does not react to him sexually at all. She becomes a Brunhilde and attacks him the more ferociously the more potentially ready she is for sexual reactions, that is, the nearer she is to spawning, in respect of her ovarian and hormonal state.

Conversely, aggression and sexuality are quite compatible in the male; he can treat his partner roughly, chase her all round the tank, and between whiles perform sexual movements and all possible mixed forms of motor patterns. The female may fear the male considerably without suppression of sexually motivated behaviour patterns. The bride-to-be may flee before the male and at the same time make use of every breathing-space to perform sexually motivated courtship movements. These mixed forms of behaviour patterns of flight and sexuality have become, by ritualization, widespread ceremonies which are often called ‘coyness behaviour’ and which possess a very definite expression value.

Since this relation of the misceability of the three great drives is different in the two sexes, a male can only pair with an aweinspired and therefore submissive female, and a female only with an awe-inspiring and therefore dominant male. Thus the behaviour mechanism just described guarantees the pairing of two individuals of opposite sexes. In many variations, and modified by different ritualizations, this process of sex recognition and pair formation play an important part in very many vertebrates right up to man. It provides an impressive example of the indispensable species-preserving function that aggression may fulfill in the harmonious play of interactions with other motivations. In addition, it shows how different the relations between the ‘big’ drives can be even in males and females of the same species. Two motives, which in one sex scarcely inhibit each other, exclude each other in the other sex in a sharp shunting mechanism.