Having been hardened by experience, many people develop a more fatalistic view of friendship

“When you’re younger, you define what it really means to be friends in a more serious way,” said my screenwriter friend, Brian. (His full name is Brian Koppelman, and he wrote and is a co-director of “Solitary Man,” a 2010 film starring Michael Douglas about a middle-aged man trying to reconnect with friends and family.)

“My ideas of friendship were built by ‘The Godfather’ and ‘Diner,’ he said. “Your friends were your brothers, and anything but total loyalty at all costs meant excommunication. As you get older, that model becomes unrealistic.”

By that point, you have been through your share of wearying or failed relationships. You have come to grips with the responsibilities of juggling work, family and existing friends, so you become more wary about making yourself emotionally available to new people. “You’re more keenly aware of the downside,” said Mr. Koppelman, 46. “You’re also more keenly aware of your own capacity to disappoint.” “I haven’t really changed my standards for what it means to actually be friends,” he concluded. “It’s just that I use the word ‘friends’ more loosely. Making the real kind, the brother kind, is much harder now.”

Some, like Ms. Degliantoni, the fund-raising executive, simply downsize their expectations. “I take an extremely efficient approach and seek out like-minded folks to fill very specific needs,” she said of her current strategy. “I have a cocktail friend and a book friend and a parenting friend and several basketball friends and a neighbor friend and a workout friend.”
“It’s much easier filling in those gaps in my life,” she added, “than doing an exhaustive approach for a new friend.” Or, they hit rock bottom and turn back the clock to their breathlessly social 20s.

After a move to New York in his 30s, Dave Cervini, a radio station executive, was so lonely that he would walk his cat in Central Park, hoping to stoke conversations. Finding only curious stares, he decided to start the New York Social Network, an activities group for people to find friends by hanging out at Yankees games or wine-tasting mixers. The company now counts 2,000 members, most in their 30s. He considers 200 of them close friends.

“It takes courage for people to take the first step,” he said. “Hopefully, I make it easier, having been there myself.” In that spirit, I recently called Brian. We joked about our inability to find time to hang out, and made a dinner date at the next available opening.It is three months from now.