My partner left me just when i needed her most- Motor Neurone Disease?

My partner silently left me after i was referred to a Neurologist with suspected Motor Neurone Disease. She just stopped contacting me and faded away. I have been there for her through her tough times, funded remodling her house, took her on holidays and generally loved her to bits. The last contact she had with me was in the car following the visit to the Neurologist where he told me i would have to be admitted for tests. While waiting for the appointment For the Neurologist my Dr contacted me to say my blood results were in and i may also have Early renal failure. In the car she asked me to tell her of my fears - i broke down - i am terrified - She said WE would get through this - I didnt know how much she loved me - Not to worry as my worst fears might not be true. She felt everything would be be all right. That was three weeks ago. I have'nt seen her or heard from her. I know she is getting on with her life. I went to see her but could not go in - i wanted her to tell me WHY? Help

It sounds like she is having a difficult time dealing with this. Not that this is even harder on you. I think you should try to call her and talk this out. It may be she still loves you, but does not know how to help you through this. Comunication is a key ellement.
Some people can't deal with pain and loss. Instead of facing it they run away. As hard as it might be for you to do this in your time of need, you need to think about the type of person she is. Ask yourself:
Does she face her problems or hide?
Did she take the time to listen to my bad days?
Was she there for any of her own friends?
How does she deal with stress in her life?
How does she deal with loss in her life?

The answers you get from these questions should help you answer your question of why. If she has always ran away from her own stresses, losses, and problems than that is what she is doing to now. If she never seem to really be there for anyone else, than she is selfish and does not want to deal with your issues.
Be open minded and think about her fears too. She may be fearing for you too. Many people who love each other deeply don't make it through the stresses an illness can cause. It is not because they don't love each other it is due to the fact they don't know what to do for each other. Remember that while being there for you she will also have to deal with her own issues from this disease. She will have her own fears and pains to deal with and try to help you through yours. It takes a strong emotional and mental person to do this and not break down. Maybe she is just not that strong and her own fears have broken her.
Try to contact her, be open, calm, and caring. You both may be going through your own hell right now. You both need to remember each others feelings.
Good luck and I will keep you in my thoughts and prayers.