Meet Bob and Mary. And Mary and Bob
I don't know about you, but I always refer to couples by the order in which I met them. For example, I was friends with Mary for ages before she met and married Bob. And they will always be "Mary and Bob" when I talk about them. "Let's have dinner with Mary and Bob." I'll say, in spite of the fact that Mary and Bob don't live in the US and we can't really have dinner with them that often.
Then there's John and Jane. John and I became friends at work and, once he married Jane, they became "John and Jane." And they will always be "John and Jane" in that order.
And this holds true for all the couples we know. Whoever I met first always comes first in the couple canon.
There has only been one exception to this rule, and for this I can't use aliases. I was friends with Tom in college and then he started going out with Jerry. Actually it was Gerry, but still....Tom and Gerry? I don't think so. Since I refused to call them after cartoon characters, they became Gerry and Tom (and, later G&T after their favorite pre-dinner drink). But that was the only time I ever broke the rule.
Is this just me or do you do this too? I think it makes perfect sense, but then again....I'm odd.