You're not the only asexual person out there in fandom. I read fics with sex in them for pretty much the same reason you enumerated up there; a huge chunk of fandom fixates on it, even if it's not explicit or all-out intercourse. But if you want to write a relationship that doesn't revolve around sex, do it! You aren't the only one who likes gen or even relationships (of whatever kind) without any sexual aspect.