Oh I'd take that seat if it was on the table. I'd offer it to my partner first, but being 6'3, that leg room would be too good to pass up for me. Plus I'd visit her often.
I think I'd stay. Having company would be a lot more important to me than having a better seat. And less importantly I might feel cold deserting her. And she might feel it the same way (or worse).
I'm staying, for both principled and pragmatic reasons - it's the right thing to do, and leaving will be Exhibit A the next time there is an argument 😛