The one thing I know for absolute sure, especially at this time of year, is that sometimes the best choice is walking away.
If you've been trying and trying and putting everything you can into it, and it still isn't what you need, that's your sign. End it, and you'll be free for something better.
We're so conditioned to think that we can't quit or we've failed. But that denies the fact that some situations aren't completely under our control. And there's huge value in knowing when to fold 'em and moving into a situation with the possibility for success.