My DH is older than me and I have had the same worry you have! We have been happily married for 38 years but I still worry that he will die before me. There is nothing to make me think that since he is healthy.

For me it has always been about fear of abandonment. Like many people, my childhood situation was not stable but I was fortunate to find a good person and the idea that it could be taken away is so scary.

I don't have answers, just empathy. Even with that constant underlying worry, I wouldn't trade these years we have had for anything.