I think many BL creators tend to write newcomer women/girls to be solely as the obstacle to the couple. This trope is still done beyond death. Sadly, it has long become a principle of BL.
So if a BL ever deviates from this principle, it comes to a shock to readers, especially the young ones. I don't blame them for such principle etched into BL. It's just a cheap element to spice up the drama. They'll eventually get tired of it and learn to appreciate women characters more as they grow. So I won't think too much about it. We can only cool them down by replying to them diplomatically and nicely.
As for the adult haters, oh boy.
I had read one BL involving a girl trying to steal Boy A by blackmailing Boy B into staying away from boy A and if not, his secret as a gay guy will be out and he has to go through all sorts of repercussions in school and at home.
I commented, praising the girl for being cunning and evil instead of pretending to be nice. She might be insecure and has abandonment issues too. And then she grows out of being malicious and makes amends with the boys. Then this woman reader replied to me, "Don't ever give that b*tch credit," even after everyone has a happy ending. 