I just realized I haven't previously pointed the metaphysicians on Less Wrong to "Possible Girls," a hilarious paper about acausal romance:
The ability to causally interact with your partner is important to many aspects of happy romantic relationships, but not to all of them. It’s quite pleasant simply to know that your partner loves you and appreciates being loved by you. A loving relationship with a faraway person can enhance one’s self-esteem and turn loneliness into contentment. As a lonely philosopher, I’ve come to wonder: If [all possible worlds exist], can I have a loving relationship with someone from another possible world? ...The answer, I think, is yes.
Even if you don't read the whole thing, don't miss the final paragraph.