Also using my grandad as an example - he stood by 2 wives that suffered from cancer.
My biological nan was diagnosed with cancer when she was only 54, and my grandad looked after her and she stayed in their home until the end. He then remarried some years later and was with my grandma (I consider myself very lucky to have had 2) for over 10 years, recently losing her last year to cancer also.
Even after being through it all with his first wife he stood by and looked after his second wife until the end - even as he was going through health issues of his own.
I agree with pp - it really depends on the person and the love they have for their partner.