I can never truly understand people attaching themselves to one game. You'd be a lot happier with playing other games and that is a cold objective fact.

Either that or just do what I do, if you like this game's world and happen to like creating characters and coming up with their own stories, actually play alts. This has been my easy go to solution to keeping me into playing this game once my main has done everything they can do, as I can go back and re-experience the older expansions with a new perspective or approach things more efficiently. If you enjoy playing the game, then you'd also enjoy replaying it again, or at least this was a thing I used to do constantly when I was a kid.