They can't hold a loved one's hand, sleep next to their hospital bed, comb their hair or shave them.
"All of these physical and mammalian kinds of signals and bonding that we share with any other species -- all of that caregiving is stripped away," said Robert Neimeyer, director of the Portland Institute for Loss and Transition.
Forgiveness can't be granted or sought. Years of estrangement can't end with a deathbed vigil. "We are left holding a bag of a lot of unfinished conversations," he said.
Stacey Silva is haunted by a phone call with her father, Gary Young, a week before he died of complications from COVID-19 in mid-March in a hospital in Gilroy, Calif. Although she had been able to see him through a glass partition in the intensive care unit, the hospital had stopped visits.
"He called me about 4 o'clock in the morning, and he had an (oxygen mask). It was already hard to talk to my dad and have a conversation because he would start coughing after a couple of words," Silva said. "I believe he was calling to tell me that they were intubating him. I didn't understand, and he got frustrated and he hung up.
"That's the last conversation I had with my dad, and I have so much guilt that I couldn't understand and that I couldn't tell him that I loved him," she said through tears. "I think about that every day."
Friends and family are giving her emotional support, "but nothing helps," Silva said. "Unless you've lost a loved one in this particular manner, you really have no idea how this feels."
Limits on the size of public gatherings and air travel are restricting or eliminating ancient rituals of mourning that help the living. Funerals are small or unattended. Memorial services are being postponed to unknown dates in the future. Families are choosing cremation for relatives rather than burial with only a few people present.
Virtual ceremonies and gatherings can help fill that void, Neimeyer said, if the bereaved are actively involved and not just passive observers. They can share memories and stories on Zoom or arrange a time when people across the country ritually light candles.
"Almost anything we do," he said, "that returns to us a sense of agency, where we can in some measure exercise choice or take action."