Undecided questions
When a woman calls a man "minh", does this always mean that the relationship is romantic?

Hi it means literally: bright, intelligent, lucid. Used for both men and women.

With your question, it is lovely and romantic way to call "minh" between husband and wife. But nowaday, most people like to to be called by their name, to show their position in family. By the way, we have more ways to call between husband and wife are calling the name of the son or the daughter. For example, the name of the son is "Nam", the wife can call : "Bo Nam" or "Ba Nam",, or contrast : "Me Nam" or "Ma Nam"...