I'm with Jaimito on this one. What century do you guys live in? Where do you get your advice on these matters? Cosmo and Maxim's?

I have given up "superior" (exit, domestic F, or international C) seats to friends, family members, and my spouse, but I would never do that just because "she's the girl." Frankly, I would recommend reassessing the relationship with a spouse who expected this kind of treatment.

Now, in the situation described by the OP, with a person who's never flown upfront, the decision to give up the seat should have been easy. Especially since they were on vacation together. But I'm sure he paid for his mistake (which, of course, may in turn negatively impact the GF's chances to get the F seat on the return).

As for "declining the upgrade," I'd be interested in finding out how you guys do that -- my domestic upgrades usually clear 5 days out, and my spouse's three. Even if hers don't clear at that time, she usually has a good shot of clearing at the gate. Pray tell, when is the ideal window of time to decline an upgrade to make sure that you sit next to your spouse in Y? At the gate, when it'll be tough to get two adjacent Y seats? Or perhaps better not put in for an upgrade at all?