I think "want" was the right choice. "sex" and "love" were my guesses. Sex would have been fun, but as you say, not sure he'd say that. "love" would have been instantly serious, and of course wonderful, but then maybe Tifa wants to hear that out of a sober cloud. I think "want" is better than "need" here, because need is something... obvious, I mean, Cloud needs Tifa, hands down. Want says something more about how he thinks and feels, and I think it means more that he wants her than that he needs her, but maybe that's just me. In any case, well done!