Here's what happens to us....
I'm the frequent flyer, husband is not. When flying together, I make sure I am assigned to the middle seat. He says if there is a one person upgrade it should be me, because I earn them and he is a sweetie.

When it has happened that only one can be upgraded, (It has several times) we have always been called up by the Gate Agent who asks is we want to stay back in steerage together, or, if one gets the UG, which one? Very civilized. I always take the UG as I said, my husband is a sweetie