He doesn't know how to react to the information, especially in this context. I mean, it makes sense, but there's so much to address in what Rico just said that he doesn't know how to properly discuss it.

So he begins with a gentle squeeze, while also stroking Rico's back to let him know he's okay with that.

"I mean... I didn't even know you masturbated until I saw you doing it" he admits too.
"And now you tell me this after we..." he doesn't finish, saying out loud would ruin the mood.

He's starting to feel warm and fuzzy, as well as sleepy.
"I mean... There's so much of you I have to understand. And I'm fine with that. It makes you even more special" he smiles, and brushes some hair away from Rico's face.