Jacob is a true bro, he has your back and is honest with his intentions. It's pretty clear that he had a crush on Zoey right from Episode 10 on the "Rooster" post with the halloween pictures. I can't really blame him for it, I'm sure most of us have been there one time: someone we liked didn't like us back and we embarrassed ourselves as a result of pursuing things.
It's why I don't blame Jacob at all, he was upfront with his intentions and didn't go behind your back. Despite Zoey being an ex-girlfriend, he wasn't a snake like Nick who fucked Tommy's girl even if she came onto him.