I'm your husband in my marriage. Hit mid-40s, felt unsatisfied at work, one great kid but already looking at empty nesting, midlife malaise, etc. Have always exercised but started doing it more aggressively (6 days a week, lift heavy, really working out to build strength and endurance and not just to maintain weight.
It has been amazing for my life outlook and mental health. I feel so much better generally, wake up feeling good, eat healthier naturally because my body needs more protein and veggies and I just crave sweets less. Sex drive is up, better attitude at work.
Also less stressed about aging, and empty nest Now look forward to retirement, being able to travel with spouse and kid even into my 70s/80s. No longer feel the good part of my life is over, instead feel like I'm just getting to the best stuff now.
Have no desire to stray, my DH is my partner, no interest in starting over with someone else.
But sometimes it does feel like he wishes I'd work out less. Or feels like now there's pressure on him to workout more. I don't feel that way -- he is fit and exercises, as long as he is happy about himself, I'm happy. I just wanted to feel good in my own life and this has really helped me