*this.I dive mainly with my dad now and he had a pretty good solution.
He bought a set of double 80s... then took my double 100s and gave me the 80s lol.
Just buy a bigger tank for yourself so you don't divorce her lol. Or buy a long hose and start the dive on her air (that may have been standard dive planning for my buddies for a while)
Same situation with my wife. "Solved" it by changing tanks. I dive with an overfilled LP108 (150cuft roughly) and she dives with an al80 (77cuft). We come out with similar reserve pressure (although that means I've got more volume). It would probably work if I used something in between a 108 and an 80, but 108's are what I've got.
Doesn't work when we're traveling and have to live with rental tanks. Often I've found our choices are al80 or al80. Sometimes al100 is an option. I've never dove with an operator outside the US that will rent steel tanks, especially overfilled lp steels . I guess I could do sidemount doubles while she does backmount single but that's a lot more work.