Well, heterosexual tendencies of some characters are made very clear.. Lots of peoples partners in heterosexual relationships are established.
yes but you can't casually establish a gay relationship. it's sad, but heterosexuality is still considered normal and everything else abnormal. and i didn't said love isn't thematized, I said sex isn't. if it had been made obvious that d. and gr. had a real relationship, people reading it would immediately think about homosexuality, which isn't jkr's style at all, and also the characters would be expected to discuss it at some point.
