Keltham finds, rather to his surprise, that he's choked up and can't actually answer that in words.
Nobody's ever told him that they enjoyed sex from him that much. Ever. Not even close. But it makes sense if he imagines that, first of all, everything you can in Civilization pay to learn how to do using careful biofeedback-based training would, in fact, be an elite sex worker service or maybe flatly not exist in Golarion. And, second, that masochists do exist there, and people who don't want to be in control, who want things to happen to them without them saying words to be in control, who want others to be powerful over them in the way that Keltham enjoyed being powerful over Yaisa, that he is sent now by higher forces to an impossible world in which impossible complements to his own sexuality exist and are common enough to be unremarkable -
He can't talk, so he just folds Yaisa into a hug.