“The first few months I thought: ‘This is OK, I can work on myself,’” said Gagan Bhatnagar, 35, a clinical oncology consultant in London. “But then it just dragged on. One day I realized it had been three months since I had touched a human being.”

With a widely shared Twitter thread in December, Mr. Bhatnagar tapped into a wide range of single angst. The thousands of responses he received indicated single people often felt their needs were being overlooked or dismissed, and they frequently felt guilty about expressing them. What’s a bit of mopey loneliness when others are dying?…

Some, especially those who live alone, said they felt left behind by lockdown policies that discourage household mixing. Even when government policies allow those who live alone to form a “support bubble” with another person, as in Britain, most close friends are already bubbling with partners or family, leaving single people uniquely isolated, Mr. Bhatnagar said.

Being unable to date as usual has robbed people of the hope and excitement that can sustain them through typical rough patches, he said. (Many reported that socially distanced walks in the cold, one of the few Covid-safe ways to meet people after matching online, wasn’t conducive to forming connections.)