No, it has nothing to do with that. Stop acting like there's some mystery here that you can't figure out.

Your wife is a young woman. She's not at "mid-life." That happens between age 50 and age 60.

Your wife is not having a "crisis." You are having a crisis. Your wife knows pretty much exactly what she does and doesn't want to do. She does not want to be with you. She has already made that decision and has moved on. She's not dealing with any crisis. She's pursuing education for a nursing career and she's pursuing finding her next man. She's interested in you as someone to do many hours of childcare during the week to give her a good bit of free time. Also, she needs you to help support those kids. Beyond that, she has no use for you in her life. Get it, know it and live with it. You are the one in crisis now . . . because you had no desire or intention to end this marriage. But it is over. She no longer lives with you. It's over between you. It's over. That's not going to change.