There are multiple reasons, actually. The main one, and the one I keep going back go is that I love her. In a lot of ways, I can't imagine my life without her. That being said, she is leaving me, at least temporally. She is moving out next month to focus on her healing. She feels it's best for all concerned if she is isolated during her treatment. I'd rather she not do that, but she insisted. She signed a 6 month lease on an apartment. Whether or not she moves back is unknown at this point.
But, to answer your question, I believe marriage is for life. She is my partner, and half of the whole that I share. I'm hurting through all of this because she is hurting. I want to share her pain, her anxiety, and her grief. However. She is keeping me from doing any of that, which is incredibly painful to me, personally.
She tells me that her moving has nothing to do with me, which on one level, I appreciate, but to me, whether it has anything to do with me, she is still moving out.
I also stay for our kids. My 16 yo daughter has seen everything from the very beginning, and I am trying to show her that there are some things in life worth fighting for, regardless of how much it hurts. We have talked about this, and she understands completely. My 1.5yo son also deserves to grow up in a house with his mommy and daddy together. I am going to do everything in my power to make that happen.
I suppose on some level, I fear being alone too. However, I don't want anyone else. She has told me that I deserve someone better than her. Someone that will make me happy. My reply has always been "The person I need is you, healthy. Let's get you there."