Nope, nothing is happening. Nothing inherently bad anyway. Around 16-17 I started to lose interest in games, though in my case that was just because I hadn't looked hard enough to find games that I actually considered interesting. I started forming my own odd interests in games around that time, and when typical shooter and RPG content became boring I thought it meant I was no longer into gaming.
Since then my interest in games has resurfaced, but only because I discovered the action/adventure genre and similar games (IE, Drakan, Dark Souls, Monster Hunter, Zeno Clash). I can easily sink 200+ hours into similar games without getting bored, but most games now are blegh. Typical shooters and slower RPGs have to be supremely epic to hold my interest for even a few hours; Dragon Age Origins is the closest they get and I still get bored with that in a relatively short time.
It'd probably be worth it to lurk Metacritic or Wikipedia to find games or genres that may fit your interests better than "Random Shooter 2014 Edition" or "RPG Fetch Quest 11: Quest for DLC." Or, my personal crappy favorite, "Totally Artsy 8-bit Indie Game #1265 Because We Couldn't Make Anything Else Last More than 2 Hours And Our Texture Artists Aren't Actually Artists, Just Phil The Guy Who Also Fixes the Photocopier."
It's also worth noting that if you have a very poor quality keyboard + mouse, the chore of actually controlling the game can make it a lot less interesting. You wouldn't think it'd be a big issue, but the small issues like hard key clicks or a high friction mouse annoy the crap out of your subconscious after a while, just like using a badly worn out controller.
If you really are just not into games anymore, that doesn't mean anything bad. If you lose interests in all of your things at once and don't want to do anything, that may be indicative of hormone imbalances causing mild depression or something, but just losing interest in one or two things is absolutely normal.