I agree with others who're saying it's due to lifestyle changes and time constraints. I'll add that it could also be due to changes in you and in gaming. Re. the first, it's possible that, like me, you've changed over the years, and you're no longer as excited or stimulated by many games, the way you used to be. You've played a lot of games, so you know what to expect. Instead of feeling like things are exciting and new, it's a "been there, done that" feeling, a sense that you've seen it all before.
There are changes in the gaming landscape, too. With bigger budgets comes more mainstreaming for wide appeal and sales. That contributes to the "been there, done that" feeling, since games tend to stick to the safe route. And there are fewer big releases now than there were 10 years ago, so there just isn't the variety and volume of big new titles anymore. We are also in a slow period.
I've had difficulty getting deeply engaged in games for a couple years now, so I can relate. For me, it's not lack of time. It's just that I don't find most games that compelling anymore, for the reasons mentioned above. I have other things I'd rather do with my time. I don't think there's anything wrong with that. I don't try to fix or change it. I just pay attention to the games that are coming out, and I look for ones that truly interest me. Occasionally I find one. Then I wait a couple more months, until another one comes along.