Do you ever think that you working on your Master's degree is making her feel insecure? You're living your dreams. She's helping you do it by paying the bills. What does she have at the end? Every now and again, she may get the idea that when you're done with school and working your dream job, you'll just go ahead and leave her for someone more like you.
I know that's how my husband felt, at least for a while. He may still feel this way.
Your wife might feel smart and experienced and sophisticated around these 18-year-old kids in a way that she does not feel around you.
Again, I don't know what the answer to any of this is. But it something to think about and maybe watch for.
Me: 28 H: 30 T: 9 M: 7
WAH: First half of 2017. Round 2 started in Spring 2018.