My daughter had 2 of her best friends die in an auto accident over 20 years ago. Both sets of parents divorced eventually. One of the Moms said that she and her husband grieved so differently that it tore them apart.
She wanted her daughter's friends around as much as possible. He could barely stand to look at them.
I can imagine that as a step-parent it has to be especially difficult to deal with the grief of your spouse.
My brother died in a car accident in 1979 and my parents might have well have died with him. Our family life was gone forever. My grandmother, who lived with us, died of a stroke three years later. My father developed cancer five years later. My mother got a job and survived, but she was gone from my grandmother and father most of the day. They had only each other to talk to, she had others. After she was alone and retired, she became an alcoholic and drank herself to death. She later said that she was proud of how well the family had coped with the loss. On the other hand, I cannot imagine how it could have been worse.