We have won plenty the past few years, and my interest level still declined. The wins are not memorable, and the losses don’t sting anymore

Just try having your team line up against your bitterest rival and not even belonging on the field or even in the stadium several years in a row with only the shittiest of recruiting classes coming in. That will give you the major depressive episode you seem to think you're experiencing right now. If you've just lost some level of interest because, well, life over time brings perspective, then you need to find some true human interests involving children or other good causes. I wish you well in your search.

more fundamental issue. Have you lost interest in other matters as well as ND football? Aging does sometimes bring about disengagement. One has to work at maintaining interest in life. It doesn't always just happen. Some things I have done include exercise, new activities, and interacting with my support systems more.