OK

As hard as it is, I would leave it be. She may be afraid to be alone if she angers him. Is there ever a time she is left alone? Maybe that would be a nice time to visit.

I know that you are probably right but it just hurts so much. I really want mum to know why I don't visit as often as I would like to.

Her partner is her life now, and yes normally the partner will come first over grown children most of the time. I honestly see no real issue in this,

And their illness is the reason for this and no they can not control it and you are not worrying about the real issue , your moneys cancer.

You need to stop putting your issues in this and consider what your mom wants

I know that you are probably right but it just hurts so much. I really want mum to know why I don't visit as often as I would like to.

I understand your concerns. Is there a time when he leaves to run errands, or goes to work?

Fr chuck - I have given this a lot of thought as I do try and learn from my mistakes. You are correct, moving forward I am going to forget about my own issues and put my mum first.