Some people lose purpose in life, some suffer great pain, physical or mental. Some lose their family and loved ones in a day, like i did, and cant take emptiness and pain that such life brings. And no, it doesnt get better after you lose your family. No "new love" replaces what you had. To some people that would be a big insult.
Reasons are many, different for each person. Some could recover, some cannot. And we cannot judge anyone, or feel what they feel. I hope this answer helps you understand better.