Another concept of fucked up femdom sexo matriarchy world building I like is how it can just effortlessly corrupt otherwise cute relationships into yandere and mindbreak
Even if there's not much of an innate biological compulsion that would have guaranteed it, just Living In A (femdom) Society means a girl who would have otherwise been a gentle, loving wife is pressured and conditioned into being more possessive and aggressive, not in spite of but because of her love. She can't stand to lose you to some other girl who'll swoop in and take you away (even if you try to tell her that would never happen) and she can't handle the idea of failing to protect you from a stronger woman out to victimize you (even if you're pretty sure you're not much weaker or stronger than her and are more worried about gossipy mean boys after your social life), so what choice does she have but to let herself be remade into an unhinged yandere muscle mommy rapist and claim you as her permanent property? Any other girl who cares about her man does the same, right? And so do many other girls that really do have the will and desire to be so much less gentle about it- really, by making you her property she's probably doing you a favor. She doesn't *really* want to make you a submissive whore of a boy stuck in a gilded cage of a house, but if she wants you to be hers, she just has no other option. Besides, guys like being cared for, right? And sex, and not having to think about things. So if she makes sure you get all of those, you'll get used to it, won't you? Her friends and family say all the other boys did, even if it took a little while... Female friends and family, that is. The men aren't usually in much condition to speak or think for themselves after a while...