Perhaps some sort of animal had come in contact with a disease that only killed or negatively impacted the females of the species, did that lead to increased homosexuality in the males of the species?
I always like animal to human comparisons and I'm just wondering if I can link the rise of homosexuality to the decrease in female quality by using some sort of animal comparison.
Doves are a species of birds that are oddly... bisexual? If you place two doves of the same sex in a cage they will become mate. One will assume the other sex and act as if it was a member of that sex. (Example, 2 female doves. One will assume the role of male and court and mount the partner but both will lay eggs. In two males relationship, one will become quieter, stop courting and take female shifts in the nest) BUT if a dove of the opposite sex appears in their life they will literally fight for it and "break up". So yes, doves will be gay voluntarily to avoid loneliness but if the choice to be straight is there they will throw that relationship aside. I havent observed if the phenomena happens because of degradation of the quality of the other sex.
Theres even wikipedia pages about the phenomenon but im learning from experience. I bought a new male for my female dove after her male died and it turned out to be a female too. (Seller didnt identify her correctly) As far as I know, birds are the only species that will display homosexual tendencies without the humiliation aspect that is present in other animals such as felines.