R. Couri Hay | The New York Times

The party was for the unveiling of a 1910 Grosvenor Atterbury mansion in Southampton that the developer David Walentas hopes to sell for $35 million. But the sprawling property didn’t sprawl quite enough for two guests in particular.

Jesse Warren, 38, the town’s mayor, and his opponent, Michael Irving, 67, had been at war for weeks in what Newsday called “likely Long Island’s most contentious mayoral race this year.”

During the pandemic, they had been able to avoid each other in social settings. No longer.

“I haven’t said hello to him yet,” Mr. Warren said while the two stood within hearing distance, backs turned. “But I’ll try to be nice.”

Ah, the perils of socializing in real life again and running into people you would rather not see. That was a nonissue up until recently, when events were canceled or moved online. Even as socializing slowly crept back in the form of outdoor dining and the occasional garden party, face coverings and social distancing made it easy to avoid intimate contact.

But now the snake-pit moments in the social fishbowl are back with a vengeance — whether it’s running into a bitter former spouse, a business associate who hasn’t returned a call, a tabloid reporter who threw you under the bus, or a socialite wearing the same designer dress.

“All these guests come out for the first time in over a year for a lovely party, and they have no idea they’re walking into World War III on the lawn,” said Peggy Siegal, the high-profile event planner who hosted the Southampton party. Ms. Siegal was organizing her first event in nearly two years after being shunned by clients for including Jeffrey Epstein on her guest lists, and she was hoping that no awkward encounters would ensue.

The awkward social run-ins are not confined to the Hamptons, of course. “Everyone’s afraid of running into everyone right now,” said R. Couri Hay, a press agent who consults on guest lists for society events. “And it doesn’t help when parties are smaller.”

Heaven help you, for instance, if you end up at the same cocktail party as a former boss whom you despise, or a socialite who took you off her list, or a celebrity friend in a sex scandal.

“Hosts right now are asserting more control over guest lists to avoid awkwardness,” Mr. Hay added, noting that unnamed plus-ones and summer houseguests in tow can be problematic. “Some of it is driven by social media and cancel culture, but it’s also driven by hosts not wanting ex-husbands to show up with girlfriends half their age who they met during lockdown.”

Some highly social types are taking a lay-low approach, too.

“Instead of yelling ‘Hello!’ when you see people you know at La Goulue, you just pass by quietly if you aren’t close friends,” said Frederick Anderson, the society fashion designer. “This past year has been so isolating and has pitted so many people against each other that it’s going to take a few minutes to feel comfortable and inclusive again.”

Others have to turn a blind eye on a regular basis. Alvin Valley, the fashion designer, keeps running into a client who borrowed and has not paid for a mink coat. “I’m suddenly seeing her at all the parties in New York and the Hamptons,” he said, “and I have to avoid her so it doesn’t turn ugly.”

For Rosie Perez, who is terrible at faking her feelings, lockdown life kept her isolated enough to avoid most uncomfortable encounters. But she recently saw a friend who had gained weight during the pandemic, and her candid reaction got her in trouble. “My eyebrows always go up when I’m lying to be polite,” she said, “which is how you can tell I don’t use Botox.”

For some, the risk of an uncomfortable encounter is so severe that it keeps them from accepting invitations.

Alexandra Petri, a columnist for The Washington Post and the author of “A Field Guide to Awkward Silences,” spends too much time scripting her responses to imaginary encounters with all the people whose emails she has not returned. “I think I will probably fling myself at the person’s feet,” she said. “This is why I’ve been trying to avoid parties.”

The awkwardness can be especially difficult for those facing social ostracism.

Kristina Kovalyuk, a political consultant who had worked on Eric Adams’s mayoral campaign, started getting shunned by clients and old friends after The New York Post ran an article in May about her being previously charged with shoplifting and selling a fake Chanel handbag.

“I ran into someone at Butterfly in Soho who I’d texted twice to get together,” she said. “He started stuttering that he didn’t know I was back in town from the winter in Palm Beach.”

She also recalled running into a potential client at Nello, who told her that he was laying low, but that they should have lunch. “Which means never,” Ms. Kovalyuk said. “People are still using Covid as an excuse even when the Iron Curtain has lifted.”

How to handle all this? The most obvious way is to just be pleasant or so radiant that you burn the ill will away.

And while some may still surreptitiously swap place cards before sitting down to dinner or stay laser-focused in conversations as a protective shield from unwanted intrusions, the more gracious among us will face the thorny issues head on and rise to the occasion.

“When you’ve done something that upsets someone — no matter who’s right — always start the conversation by acknowledging how your actions affected the other person,” said Peter Bregman, the host of the “Bregman Leadership Podcast” and a contributor to the Harvard Business Review. “Save the discussions about your intentions for later.”

But breaking the ice doesn’t need to be heavy. Sometimes it’s as simple as saying “hi.”

“When I know people are fighting and they show up at the same party, I bring them together and it gets them talking,” said Patrick McMullan, the society photographer.

That’s what he did at the Southampton party, when he got the two mayoral candidates to shake hands for a photograph. (Mr. Warren won a second term a week later, though Mr. Irving said there were voter irregularities.)

Ms. Siegal, who sailed through the party without an awkward moment, looked pleased. The mayors had behaved. “They didn’t even argue or have a food fight on the lawn,” the event planner said.

It was hard to tell if she sounded relieved or disappointed.