He absolutely can fancy who he wants.
I bet Caspar wishes he had just said nowt. Or just said that she was the spit of his sister.
I’m all for honesty. He doesn’t fancy her. For whatever reason. But sometimes you can be smart enough to not be very very truthful with someone you have just met if you think there is a smidge that they’d be offended/hurt. Not smart.
And he did hurt her because she can’t let it go.
But by the same token, it is not smart to let someone hurt you like that. More so if you don’t know them from an egg.