He didn't get iseaki'd, but my theory is that in between the "tutorial" with the White Succubus and when you actually gain control, he went around and got lots and lots of wives. That's how he somehow already has the scents of multiple mamono on him, as some of the girls notice, and so maybe some of the "boss" girls will be "former" wives who are overjoyed to see him and basically be super aggressive to try to get him to abandon his quest for 24/7 boning. Note that he already has "Incubi skills" (aka he already got transformed by a wife) at the start of the game.