This is a common occurrence for me since I don’t have much time to play. I often get about halfway through and then stop playing for months. When I come back to it I always want to start from the beginning and then the cycle happens again.
One example for me is Fallout 4
I’m gonna break the question a bit, because I finally beat it earlier this year…
But it took me 12 years and God knows how many characters to beat Skyrim