One other option, if you don't want to invest in the split king or deal with the sheets and stuff. My dad's widowed, and the only one sleeping in his bed. But he has spinal problems that make lying flat uncomfortable. He looked into an adjustable bed, but didn't really like the hassle, plus it wouldn't have solved the issue for travel. Instead, he bought a foam bed wedge system. It's three pieces that can be put together in lots of different ways to make a bunch of adjustments, and just goes on top of the regular bed. And they're easy to space bag for travel--the two smaller pieces in one space bag, the larger piece in a separate bag, then both together into a single garment bag.
The whole system takes up one half of a full bed, so you could easily each have your own on your side of a queen or king bed.