Someone who is sick is said to be "suffering" from an illness. If it doesn't kill him, then his suffering will be over before long. And if it does, well then his suffering will be over then, too.
So suffering doesn't last forever.
But what about Sisyphus? His suffering lasted (and continues to last) forever. Now that's suffering!
When loved ones die, people take some comfort from knowing they didn't suffer. Why is that? When a person travels alone from Death minus one minute to Death, does it matter at all what the person encountered on that road?
We believe that people can suffer. We believe that dogs, horses, and even fish can suffer. But do germs suffer when we spread disinfectant or antibiotic on them? Do trees suffer when we chop off their limbs? Do machines suffer when we make them work without giving them the proper lubrication? How can your answer be "yes" to one of these questions and "no" to another?