I read this book a while ago. This was a few years ago, but recent enough that I got it digitally.

It was a fantasy book. The setting was kind of weird, something halfway between a historical romance and off-brand DnD. There was magic, but no races other than humans.

The MC was a young man in training to become a preist/cleric/monk/something, and FMC was his traveling companion, secretly his goddess, having assumed human form for unrelated reasons. He angsts a bunch about being torn between his commitments to the faith (including celibacy) and his attraction to the FMC (who is, again, his goddess).

Because this is DnD logic, he can heal people. MC also had really bad self-esteem and self-loathing issues, and when he's frustrated he punches things until his hands break and heals himself.

FMC is a literal goddess, MC is a golden retriever subby good boy with issues.

Medium Spice. Hot scenes involve creative misuse of magic.