Romance might also have the component of willing sacrifice, which I think loses something when discussed as only a tit for tat exchange. The desire to please another, to surprise by a lessened burden. It is, of course, not a thing that happens only between sexually attracted people, but it seems to me that finding a friend with whom I could maintain this level of trust is...at least as hard as finding a romantic partner.

I do have a twin, though, so I very much agree that it is possible to love someone without desiring them.