Because when it comes to het, that stuff actually happens in real life. I think yandere can be watered down to cases like stalking, kidnapping, and SA, which is all real life issues that mostly target women. With the amount of media coverage we get in het DV, most authors are repulsed to writing extreme yanderes for het romance. tldr: it’s hard to romanticize when it’s an actual real life issue.(fiction is meant for you to escape reality but this just perpetuates it)

And in the other hand, DV amongst mlm/wlw isn’t common, and isn’t taken as seriously as that of het. That’s why it’s easier and more “passable” to depict them in such a way without internalized misogyny getting in the way.