Nuance of マスター vs. ご主人 when referring to a cafe owner


I'm reading a story where the main character debates whether he should call an
cafe owner マスター or ご主人. At first he says the former doesn't fit this person,
so he uses the latter, but after a conversation the owner asks him to use the
term "マスター"

I looked up these two words in a dictionary, and マスター seems to correspond to
"barkeep" or "master" and "ご主人" with "owner". However, none of these words in
English are something you commonly use to address someone when speaking to
them.

If someone can tell me the nuance between these two words, and any suggestions
to map these to appropriate terms in English, I'd appreciate it.

(The story is [here](http://ncode.syosetu.com/n2337dj/2/) if you want to see
the context)




As a native Japanese speaker, master sounds more natural when referring to a
cafe owner. ご主人 is not grammatically wrong though but ご主人 sounds more formal
and appropriate when referring to someone who is much older than you. You can
also call ご主人 for someone's husband to pay respects.

Example : So what does your ご主人(husband) do (for a living)?

Hope that helps.

