I mean genuine question : why does it matter that they leave women for men or other women, though? I definitely get the argument of some bi girls (more often than lesbians) not wanting to put their part in the relationship and still wanting it to be heteronormative, trust me I had issues with girls like that first hand and that's actually a very valid concern for a relationship to fear it'll be expected that it is one-side. But why does the gender of the person they leave for matter? I doubt in many of these cases it's as much a matter of specifically quiting a girl for a dick than just quiting a girl for someone else? To my understanding, that's not how being bi work?