Although the question has been pretty much answered already, I just want to express my personal opinions. I (like most
normal guys) am attracted to yuri, but not to yaoi. Bishounen, though, I can accept (and even have a few walls of those,
out of thousands), but it has to be technically great at least. Same for cute, and girly things. As for romance between
2 guys..., I prefer to stay out of that, unless it's comedic. Anything further, I will NOT tolerate.
Enough about me, let's get to the point. Girls like yaoi, because they are usually attracted to men, and if 2 (or
more) of the guys they like are together, their fantasies will flourish, and they'll imagine being part of it. Also
the guy's original female lover won't exist, basically giving the girl a "chance" to "be"
with them, although in real life that is undeniably false. Just my theory.