I do think trust is needed. In any game, you trust the other individual will follow the rules. You also trust that they'll do their best to win (if on your side, be a partner, if opposing you, to not simply let you win). But no, I don't think love is required, not even love of the game as suggested by jos. I don't think you even necessarily have to like each other. I recently watched a Big Bang Theory episode where Sheldon was out for revenge against his "enemy" Wil Wheaton.
I think the biggest difference in playing online video games with others is that you can be anonymous or even invent an entirely new persona for yourself. On the one hand that might increase personal enjoyment, but on the other it could distance you more from others.