He lost feelings and is seeking emotional validation elsewhere or he thinks you’re cheating. The only solution is to ask very calmly about it. (I only say he thinks you’re cheating because I was in a similar position where I stopped doing that for my ex boyfriend because I thought he was cheating on me, so I stopped being affectionate)

Do not contact Diane. you need to get into couples therapy immediately so you can discuss this with your wife. Your brain is just seeking out the only alternative that I can find to help you cope with the experiences you’re dealing with at the moment. But whatever you do, do not contact Diane she has nothing to do with the situation and it’s totally unfair to try and bring her into it. it seems like your wife has gone through a lot of trauma and she would also benefit from seeing either her own therapist or a group therapy for people who have dealt with parental loss, esp cancer. Don’t throw away an entire life and family on a whim. That being said as someone whose parents stay together for the kids for 25 years, don’t let that be your only reason to stay either. Therapy is the answer.