True, you can't force interest, but I can't wait to see the Cursed Blood can of worms being opened by this (Divinity 2 reference, just google cursed blood surface)
But it's not that he's not interested in her, he claims he's not interested in humans, which isn't really how it works. Besides if he's interested in her when she's in her cat form, he should acknowledge her human side as well. Imagine if he was like "oh sorry, you're not purebred cat? I'm only interested in purebreds, get off me." As it is, he just trying to use her for his pleasure in form convenient to him.