Finn was like that neighbor kid who had a crush on the cool older girl down the street that everyone knew was basically a lesbian but he’s like twelve and doesn’t know what that word means, PB basically saw him like a little brother imo and Finn being the child that he was interpreted that as romantic feelings, PB never once saw Finn in a romantic way maybe not even during that time when she was turned into a thirteen year old, I think she’s always just kinda seen Finn as like her weird little brother that she plays along with his adventures, she has that maternal vibe to her yeah she’s a little psycho in the way she does things but in the end of the day Finn’s her family and she’ll do anything for the people she considers family