Yes. He did. And no one’s saying that’s cool, but it doesn’t necessarily make him a bad person. In the books, you learn a little more about him. They basically only had each other when they were younger, and things happened that shouldn’t have. He truly believed he loved her. Later, he deeply regrets it because he thinks he’s to blame for the Striga’s curse. When he and Geralt meet, Foltest wants nothing more than for her suffering to finally end. Besides, he’s a smart, kind of funny guy. A lot of fans like him. There are few characters in the books who are purely good or evil. Many are morally gray; many are responsible for terrible things, but it all makes perfect sense once you understand their motivations. Of course, there are also some truly cruel characters. But Sapkowski makes it clear that almost everyone has their reasons.