<human>: Condense the text into a few key points

My girlfriend's mother has been diagnosed with late-stage cancer and it doesn't look good. By most estimates, unless she receives some really advanced treatment she might not make it through a year. 

I'm not terribly good at dealing with things like this, but I want to be there as much as possible for my girlfriend. I want to make sure I'm not acting dismissive, but at the same time I don't want her mind to constantly be on her mother when she's around me. I want her to be able to see me as a source of comfort and relief to get away from everything. But it just seems to me that this balance is going to be hard to find moving forward. 

Do I mention or ask about her mother often? Should I initiate conversations about how we're dealing with this? If there's anyone out there with some experience on this issue, I'd greatly appreciate your help.
<bot>: GF's mother diagnosed with late stage cancer. Need help in deciding how to conduct myself around her and be sensitive/supportive without being intrusive or constantly remind her.