While there have been games I spend a lot of time with only to stop playing, I have made it a point to try to go back and finish them. Sometimes it may take me weeks, months, or even several years to go back to them, but I've always tried to.
With one exception.
I sunk a lot of time into Destiny. I wanted to give the game a chance because it was Bungie. I was apprehensive about getting an online-only game The core combat loop was satisfying, the art design was great, and I liked exploring to find new areas, but over time the game started to wear on me. First it was the fact that on more than a few occasions I couldn't even play it when I wanted to. If my internet was out, or PSN was down, or the game's servers were down, I couldn't play it at all. All it did was remind me why I was opposed to online-only games in the first place. On top of that, over time it became clear that the real goal of the game wasn't to enjoy a story or defeat an enemy, but to farm loot. It was a never-ending grind for better weapons, better gear, and the materials needed to get those things. The game had no real end. I found all there was find, and fought all there was to fight, and having to do it all over and over just to get better stuff quickly lost its appeal. One day, maybe a month or two after the first expansion, it just started feeling more like work than fun, and I dropped it, having never picked it back up. Honestly, it would have been better off being a standard offline single-player experience instead of a quasi-MMO.