Fear of Partner’s Death

Hi, I noticed a scary feeling floating around, and did the following model:
C – my partner
T – I’m afraid of him dying
F – terrified, worried, justified
A – hold myself back from loving him as fully as I’d like to
R – not have as awesome a relationship as we could, and then still be left alone but without the great experiences and memories I could otherwise have

My partner is 55 and while he’s healthy, he has a family history of various medical issues and the men in his family often die young. I’m using this history to justify some level of indulgent worry. Realistically there’s little to “do” to help the situation (he’s an avid cyclist, and his diet is reasonably healthy, and he’s in generally good health), but I’m having a hard time finding alternate thoughts to replace the intermittent worry and panic.

Would love some ideas to help get me started… Thanks!