It doesn't seem like he's asking for sex so much as constantly focused on it. I would say he's obsessed, and that it's an unhealthy obsession.

What the hell to do about it I don't know. I saw myself becoming like that and am trying to stop it. I suppose it needs to have direct consequences that he can link to his obsession before he will see it as a problem enough to want to change. I guess that's true of most issues though, so nothing earth shattering there.