Interesting--what makes you see J/L in a different light than the other romances? To me they all seem very much the same. They are, I suspect, supposed to all be "meant to be," only since this isn't a grandly romantic universe "meant to be" means you get married and have kids that go to school. As someone has said, in this series being in love makes you an asshole--so all the relationships involve people either fighting each other or fighting as a united front against other people. James and Lily included.

I think there are probably plenty of relationships people naturally see as more interesting--with Harry/Luna, for instance, I think the Luna character pushes more buttons with Harry. Ginny always makes him feel safe and okay with himself, even when she's disagreeing with him. Luna's got that icky outcast thing that scares him (though probably nobody who knows him would ever suspect how obsessed he is with that). I think it often comes down to preferring the characters behavior with one person over another person.