Wow on all the negativity here.
You don't just pack up and go when the going gets tough, you push through and fix it.

Most of the time the issue is communication.

Are you perfect? Is there something you're not giving her? Are you making her feel loved and wanted? Did you let her take the role of the man because you're not taking it?

How do you see her? Where is your focus? Is it on her flaws or on her strength? Why did you get together?

Close your eyes, see your best times in front of you, feel how it makes you feel, see the good things she did and does.. Give power to that feeling, appreciate her for the good she does, tell her those things.

Be the change.. You don't just simply get to walk out, unless you want to be a soft, whiny boy.

You find out what's wrong and be there for her.