Yes, somebody pointed out to me independently of my comment to this review that I probably didn't like the film because I don't like rom-coms. That's close to being true. I don't actually know much about the genre because I could count on half the fingers of one hand the number of rom-coms I've watched.
They aren't my cup of tea, so it's not surprising I didn't enjoy one just because it features gay and bisexual main characters.
I have also been told, on the other hand, that the book is a lot more serious and grounded in reality. That makes me wish the filmmakers had chosen a different genre for their adaptation. But then, as you say, plenty of people did enjoy it, so I guess what I would have preferred isn't really all that important.