[bourneavent]

That's because they call you "Daddy" in the bedroom.

There's actually sort of a real reason for this. In the traditional monogamous or even polygamous relationship throughout human history it's usually the Male taking care of the female. Women when seeking a relationship are sort of searching for a caretaker that has sort of father like qualities of having enough resources to take care of them, taking a dominant role... etc.

The relationship most similar to it is father and daughter I can sort of see why the linguistics have sort of merged.

Obviously, in the last century, things have changed and the etiquette of relationship dynamics need to be spoken of in a way that's more egalitarian.

But you can't completely deny millions of years of human anthropological behavior. If men usually played more dominant/caretaker roles in relationships in the majority of civilizations, then along that timescale certain behaviors become a bit ingrained biologically through natural selection. It's not surprising to see these attributes creep into language.

[waveBidder]

Poppycock. until recently, in agricultural societies, families (usually men) were choosing families to cement relationships with by trading children. what the woman (and frequently the men) wanted was mostly irrelevant. see https://scholars-stage.org/against-human-sexual-selection/

If "daddy" is a thing, it's because of frequent age differences, since pregnancy is extremely hard on your body (fatality rates as high as being a soldier in a warzone until the advent of modern medicine).