They badly mishandled Finn's breakup with FP though. Finn did act like a tool, but he had a lot working against him. As the last human he was going through puberty pretty much without guidance. Biological parents MIA, adoptive parents dead, and the closest thing he had to an authority figure was Jake. Jake, despite being an idiot, was in a stable long term relationship and fancied himself a ladies man. All made even worse by the Cosmic Owl showing up in one of his dreams (for those in the back, the Cosmic Owl is a portent of prophetic dreams in Adventure Time, and is objectively real in that universe). Finn got bad advice from the best source available, and it backfired massively. Was Finn in the right? Hell no. But I always felt like a permanent breakup with FP was a wildly disproportionate consequence for what he actually did.
TLDR: Everything is Jake's fault, as usual.
Adventure Time double post after catching up with the topic. Fite me.