It's not humanly possible to love someone forever unconditionally. The relationship would seem pointless if you didn't get something out of it--I do not necessarily mean anything as overt as sex or reciprocated love. But anything, even if it's nothing more than the target of affection's presence, or appearance of presence.
And if things were not this way, then things would go wrong.
That's partially the premise of A.I. Artificial Intelligence (the movie). Watching it last night, after having purchased a copy at Hollywood Video on the way home for only ten dollars, I was impressed by how very good a movie it actually is. I really don't remember being so impressed when I saw it at the cinema and I think this is probably another case of a movie viewer experience effectively being ruined by my fellow movie-goers.
Anyway. It's a movie that deserves more attention.