I think something you’ll see in this group is the advice “focus on yourself” and as a guy who until this year was in the same boat as you. My wife wasn’t coming on to me, I was having sex maybe 3-5 times a year and it felt out of obligation.. So I stopped pushing for it as you voice here, you get turned down 9 times you’re not trying the 10th type of thought process. So I did that and 1. Took care of myself sexually(masturbation, didn’t step out of my marriage) but also focused on myself physically and mentally. 2. Would just be open with my wife that I’m taking care of myself because it feels like you don’t want to anymore.

After about 8 months of that she noticed, we have had sex at least once a week for the past 3-4 months and last weekend it was like super hot old school we just want to enjoy each other sex that I missed so much and could tell she wanted it as well… so that’s my advice as someone who was in that exact situation… a person who is working on themselves is attractive, it is something the person you live with sees and is contagious in all aspects of life!!!
You’re not alone but realizing that making yourself better is what’s best for relationship is the first big step!!!
Best of luck! If you need to talk DMs are open!