Can a guy and girl live together without eventually having sex?

Sure, on paper the answer's "yes", because we're all such rational beings. But people get lonely, people get drunk, people get lusty... I think it's inevitable that a young guy and girl living together over a period of at least a year will eventually have sex. This isn't wishful thinking on my part... I already live with my partner. It's more to do with a friend's situation. Thanks for any answers.