I wonder if Nanami haven't sex for 3 whole years without Asuka.

I think him saying he focused completely on work so he could get back to her is supposed to hint that he didn’t.

He's a man dear, it's 10% possible that he didn't.
But a man's thirst is unbearable compared to women.

He’s a made up character that an author wrote. I’m 100% sure that the author was conveying to us readers that he was celibate and waiting for her with that panel.