I'd suggest Alta. It has a good ski school (they don't rely on foreigners, which is always a good sign), good terrain AND it's more mellow. A lot of the resorts have a problem where beginners/careful skiiers are being buzzed by idiots... quite a few of the named Utah resorts also have really poor learning terrain too, where beginners have to make big jumps up in terrain at a very early stage. Not good, especially for women.
So Alta fits the bill. Good ski school, good learning terrain, less crazed twits flying around like asteroids, and also plenty of good stuff for the partner to go jump off. And nearby you have some places where both could go ski when the lady became confident - Solitude and Brighton, which are also fairly mellow.