YA bartender w/ ghost friend - series

A co-worker (in his mid-20s) remembers a series that he read in high school - main character is a bartender whose friend dies, but comes back as a ghost to give advice. There's also a romantic interest at some point in the series, my co-worker remembers that in one of the books, bartender finally gets together with the girl he's been after for a while. It sounds vaguely familiar to me, but I can't place it, either. Anyone?

Maybe Prowlers and its sequels

That's the one! Co-worker is very happy now. Thank you!

You're welcome!