Most people at some point fear never having experienced a deep lasting loving relationship with someone they can count on through ups and downs.
Death and the unknown on the other side of death still scares a lot of folks as well. We learn early on in life that we are going to die and yet most of us do not sense any urgency to live our lives with passion.
We act as though we have a thousand years to live. It's not until we get a shocking medical report or a sibling, best friend, or co-worker, that is in our age group that temporarily causes us to reflect on our own mortality.
Even then we want to find out (what they did) that played a part in their deaths so we can "rule it out" for ourselves. "He was obese", "She smoked two packs of cigarettes per day." or "He was a heavy drinker". There is always "something" we can point to.
The reality is if you ran 10 miles per day and lived on water and veggies you aren't going to escape dying.