Good

2 questions to think about:
1) Is he/she good TO you?
2) Is he/she good FOR you?

If your answer to 1 was yes, good! Because if he/she isn't good to you, get out of there asap. There are many others who wish they could be in his/her place to be good to you.
Then if you answered yes to the first qn, we now look at qn 2. If you answered no the qn 1, don't bother answering 2.
Is he/she good FOR you?
Has he/she changed you to become a better person? Are you motivated to change for him/her to become better? Are both of you improving because of each other?
If yes, stay with him/her.
If no, you could choose to stay, if you don't mind. But just note that if you happen to meet someone whom you can answer yes to for both qns, he/she will easily be displaced.
Someone who is good to you can easily be found. But someone who is both good TO and FOR you, is just the one you want.

Oh and for materialistic people, if you answered no to both qns, make sure he/she is damn effing rich. And I mean really really really rich. You may get verbally/physically/emotionally abused, but you get all the LV,prada,Gucci bags,shoes,clothes and anything you ever wanted that normal people can't ever have.
Pretty good trade off huh.