>>13 I mostly agree with you, specially on the friends issue.

Now on the importance of sex... I'm less certain. You can live without sex, but I'm not sure you can maintain an healthy relationship without some healthy sex to go with it, unless both partners really are or have become assexual. Otherwise someone or both will get frustrated.

As for sex for the pure enjoyment of it, I'm even less certain, unless it's opportunistic: you meet someone at a party or a bar, feel like it, it's reciprocal, why not? I'm much less certain that regular sex with someone without feelings would work out. Like you say, feelings of emptiness and loneliness would overpower any benefits of sex. It's well known (but I myself have no experience with it) that clients of prostitutes often want a chat and a bit of human warmth at least as much as sex.