So this isn't one of the obvious interpretations to most people, but it's my favorite, and the one I hear every time: "the seaside" is a code word for sex. The guy has just recently found out that his girlfriend is asexual, and he's trying his best not to pressure her into anything she doesn't want, but it's really difficult for him, as he's very much a sexual being. "I'm not trying to say that everybody wants to go" = I understand that asexuality is a real thing "I handled my charm with time and sleight of hand" = I wore you down even though I wasn't exactly what you wanted (and vice versa for the counterpart line) "But I'm just trying to love you In any kind of way But I find it hard to love you girl When you're far away" = I still want to be your boyfriend in any way you'll have me but it's difficult for me to feel like we're together when we can't really touch in the way I associate with relationships "But I fell in love on the seaside On the seaside In the seaside" = I fell in love with you while I was inside of you and I miss that feeling it's so sad and I love it because it's about what happens when asexuality isn't normalized and people don't feel they can be upfront with each other about what they really want out of a relationship from the beginning.
TMI!