“Want to read quietly next to each other in Riverside Park?” I texted a friend one Sunday afternoon in July. I was exhausted from staying out too late the night before and filled with the dread that clings to those final hours of the weekend — but I didn’t want to be alone. “Meet there at 1?” she wrote back and I packed my backpack, excited to spend another afternoon both alone and together with a friend.

The term parallel play usually refers to young children playing independently alongside one another, but it can also be a valuable way to think about adult relationships. Mildred Parten, a sociologist, first identified the concept in her 1929 dissertation as one of six categories of group play in early childhood. Although not a discrete developmental phase, engaging in parallel play is an important part of how toddlers learn to interact with others, share and become social beings. Think about kids quietly building their own separate towers with blocks or running around the playground without really interacting. Though they’re not engaging with each other, these children are also not playing entirely alone.

For adults, what makes parallel play different from two people ignoring each other in the same room is a secure foundation underpinning their relationship, explained Dr. Amir Levine, a psychiatrist and a co-author of “Attached: The New Science of Adult Attachment and How It Can Help You Find — and Keep — Love.” “Parallel play is one of the hallmarks of secure relationships, but it has to be done right,” Levine said. “It’s all about availability. If you know that the other person is available and that if you need them, they will pay attention to you, then you feel secure.”

When you don’t have a secure relationship, attempting to act independently of your friend or partner while sharing the same space can backfire. I’m often reminded of a Reddit post that went viral last year about a 33-year-old man who destroyed the blanket his 21-year-old girlfriend spent six months knitting because he was feeling ignored. Levine said: “The same behavior can be seen from two different places: If the person feels secure, they will not mind the knitting, etc. It will feel magical to be able to do things in parallel under the same roof. But if the person feels uncared for, then these things make them feel alone.” Theoretically, in a more secure relationship, he could have taken up his own living room hobby and spent quality time with her.

Indeed, the existence of parallel play in a partnership can be a bellwether for a healthy one. Sean Westaway, an IT director in Raleigh, North Carolina, said he and his wife, Shanna, often played separate video games, read or do crossword puzzles instead of coming up with activities to do together. For Westaway, thinking of the time they spend “playing” independently together makes him feel calm. No one is looking for control or getting stressed out trying to agree on something to do. After spending so much time under the same roof during the pandemic, he now views parallel play as a critical part of their relationship.

While it may seem strange that being actively there for your partner makes it easier to seek independence from them, it’s actually an example of what psychologists call the dependency paradox. “There’s a direct link between feeling securely attached and the exploratory drive,” Levine said.

Although adults don’t play in the same way that children do, we can still approach the world with curiosity and a drive to explore. Often when we feel safe, that drive increases. But, Levine said, “if we feel that our partner is not there for us, we develop tunnel vision and can only think about the relationship.” In this way, secure relationships give us the peace of mind to develop independent interests.

Sara Fowler, a creative writer in Washington, D.C., said writing alongside her boyfriend helped them spend quality time together on weekends when he had to work. “Most weekends that I visit him, he sets me up with snacks and drinks,” she said. “It’s honestly an A-plus couples activity. I like supporting him in his commitment to his work and appreciate his encouragement of my writing goals. It’s a pleasant, low-pressure way to spend a few hours in his company.”

Romantic partnerships aren’t the only relationships in which parallel play signals a secure attachment style though. Sierra Reed, a creative and social strategist in Brooklyn said her closest friends were those she could be with and “do nothing.” She can work while a friend cooks, for example. And engaging in these independent activities while being together makes Reed feel closer to her friends, she said, not further apart. “They are the people I can just be with, feel the love and think, ‘This is perfect.’ ”

Parallel play might also provide a clue as to why some roommates fared better than others during the pandemic. “During COVID, we couldn’t get away from the people we live with as often as usual,” said Dr. Jessi Gold, a psychiatrist at Washington University in St. Louis. “While I don’t think we always need ‘alone time,’ sometimes we need ‘being together, but not actually interacting time.’ It’s a way to know that someone is there, that you aren’t alone, like a safety blanket while still being able to do what you want to be doing. It allows you not to get sick of that person you care so much about because you are doing something with them 24/7.”