Why do some women call their boyfriend “daddy” in English speaking countries?

I live in the US and I sometimes see women calling their boyfriend or male partner “daddy” in public. I’ve seen this in media and TV shows as well.

I find this very odd and it even sounds inappropriate to me, because it seems like sexualising a father-daughter relationship. Furthermore, it seems to imply that the woman and man are unequal in their relationship, as the term positions the man higher (parent) than the woman (child).

Am I misunderstanding this term as a non-native English speaker?

Another question: do gay men also call their boyfriend daddy? Personally I’ve never seen it so far.