"I think he realized they're just whores who love big dick"
He's specifically talking to Anami and that really doesn't seem to be the case for her. Like she does like his big dick but she also is relatively serious, hasn't had a bf in the mean time, explicitly mentions there are other things she likes about him.
I think it's more he hasn't seen her in years and it was just a high school crush. Also for someone who absolutely wants to have a monogamous relationship his condition is still an issue.