He's a year about it: traveling the galaxy, studying.
Sex is like anything else. It's a skill; it can be learned. He seeks out acknowledged masters of the art on every planetoid and station where they dwell. Whorehouses, monasteries, gymnasia -- and not just learning to fuck, either, practicing everything which could be remotely useful in the context.
A pearl-diver on a remote moon teaches him to hold his breath for eight minutes, submerged in icy water. A crash course at a very exclusive athletic school improves his strength, stamina, flexibility. A wrangler teaches him to do stunning things with a whip (and how to lasso blue beasts with three heads, not that he asked for that lesson).
He has sex with men, women, neither, both, alone and in combination, in an increasingly implausible array of configurations. He fucks and he is fucked and he does not enjoy it, not even a little bit, but it's all in the service of a greater good.
Deina announces his return to Astinas by sending Valentine another invitation to drinks and conversation. He has some catching up on the political landscape to do, after all.