There's so many games I've stopped midway to never return:
Skyrim: About 20 hours in, I realized the combat was never going to get better and lost interest completely.
Horizon Zero Dawn: Bought it at launch but then a few weeks later Breath of the Wild came out and I told myself I was just going to try it out a bit before returning to HZD... I got completely hooked by BotW and left poor Alloy hanging.
Spiderman: Loved it, played a good 25 - 30 hours doing every side mission I could then the fucking drone missions killed my enthusiasm for the game. I think I'll eventually complete the story though.
God of War: I've done the main story and most side quests, I only have the Queen Valkyrie left to kill but she's a bitch.
Kingdom Hearts III: I'm at the Monster's Inc planet now and I'm bored with it. the combat is tedious, the story is bad, I don't think I'll comeback.
Mario + Rabbids: Put in about 15 hours into I think but it got overshadowed by other games.
Xenoblade Chronicles 2: I'm at the very start (5-10 hours in) but didn't get hook and moved on to other games. From the comments on here, I should really give it another try. If I do, I'll start over from the beginning.