Not just that I guess.
He and Oliver were best friends, he's sort of accepted that Oliver's with Shado and that's fine but when Oliver "gets" Shado killed, he's angry because Oliver's supposed to be the one to protect Shado, and now all of a sudden Oliver has a new girl.
That and the fact that being on an island for years makes you insane, and also having your best friend stab you in the back to go work for Fyers, and that fact that he is injected with Mirakuru, and also the fact that he sees twisted evil Shado.
I do agree that he needs to get over it though.