I have a theory that Percy didn’t think girls liked him romantically, not because he didn’t understand there advances, but because he thought no woman would like him that way. Think about it, Percy might have low self esteem because of Gabe’s abusiveness which would cause many problems. One of which would be him thinking that “There’s no way a girl likes me like that.”. I know there are other instances of him being oblivious towards other things, but in this situation, I think there is more than just pure obliviousness. I know that some men, myself included, think 2 things when it comes to romance and women, especially at Percys age. 1.There’s no way they like me, and 2.I would just get rejected, because of our low self esteem. And low self esteem can be caused by many things, including an abusive figure whom always puts you down. So maybe he is not as naive as we all think, maybe he just can’t see himself deserving of all the love and happiness.