Please excuse the upcoming Seinfeld moment.
Have you ever considered the origins of couple’s phraseology, a.k.a., the manner and order of how one refers to the two persons who comprise said couple? For instance, yesterday I went to Jeff and Darlene's house to visit with Candice and Luke and, while there, enjoyed a visit with Kyle and Ashley.
Which comes first and why? Do we refer to a couple based on whom we've known longer, are related to or like better? Is it flow of the tongue?