I like to think of romantic relationships as partnerships between equals, and not as some sort of "ownership" or "possession" or whatever.
EDIT #over 9000: I'm having a really hard time conveying my thoughts, and this is coming from someone who is a native English speaker. What I'm trying to say is that when people are in a romantic relationship with each other, I don't see it as them "owning" or "belonging to" each other, but rather, I see them as partners or co-collaborators in a romantic endeavor.