There are many types of friendships. Adults in the United States often say they have friends who fit into a certain niche in their lives—gym buddies or work friends, for example. These relationships can come and go as life changes, ending when a person changes jobs or loses interest in a hobby.
Then there are the close friends you know very well, the ones you can count on when times get tough. Many American adults say they have very few friends who fit into this category.
While best friends who last forever are rare, those who stick with you through the years—through work, moves, relationships, arguments, losses, or actions—stay with you for life and feel like family. So what makes friendships so enduring that they stand the test of time?
Robin Dunbar, a psychologist and author of Friends: Understanding the Power of Ourselves , says that it helps to have shared interests, hobbies, and backgrounds. Relationships matter. Dunbar’s research suggests that there are seven overlapping factors that are particularly important for forming strong friendships: speaking the same language, growing up in the same area, having similar work experiences, and sharing interests, thoughts, and feelings. Not every pair of close friends will have these characteristics in common, Dunbar says, but the more they share, the stronger their bond will become.
While the “opposite attraction” stereotype is old, research shows that “we are more attracted to people who are similar to us,” she says.
Research by Jeffrey Hall, director of the Relationship and Technology Lab at the University of Kansas, has also shown that people need to spend a lot of time together (at least 300 hours) to become good friends. Friends who can express their deepest feelings and emotions to each other will form stronger relationships than those who only scratch the surface, Hall says.
Aminatou Sow, author of Ann Friedman’s Great Relationships: How to Be Closer to Each Other , says that communication is key to maintaining a healthy relationship when you’re close to someone. So friends in the same boat don’t necessarily need to see each other often, but research shows that maintaining friendships is important.
Affirming the future, telling your friend that you want them in your life for the long haul, and cultivating a sense of togetherness are great ways to do this, he says. A “ritual” could be as simple as sending regular emojis or scheduling monthly phone calls. Or we could look to the world of family and social relationships: going on annual vacations with friends, celebrating birthdays and life events together, or even just spending the day together as friends. “It’s the little things that make magic happen,” So said. It’s real “magic,” Sow says. When it comes to close friendships and why some relationships end, he believes science doesn’t have all the answers. “You can’t predict who you’re going to fall in love with, whether it’s love or platonic love,” he says, and it takes work.”
Hall acknowledges that some of the best friendships have their flaws. Studies show that it takes a long time to build a relationship, but the difference, he says, is that when people become best friends, they can go months or years without communicating and pick up right where they left off. Sometimes, Hall says, “once a really strong friendship is formed, it never ends.”
How would your best friends describe their relationship over the years? TIME magazine spoke to two longtime friends to answer that question.
Amy Kohn, 69, who lives in New York, and Madeleine Rudin, 69, who lives between Florida and Connecticut, have been friends for 65 years.
MR: We grew up across the street from each other in New York. We met on the playground and started kindergarten together the next day. We went to school together for 14 years. We hit it off right away.
AK: I always felt like a misfit in school, so having a best friend meant everything to me. Madeline helped me through the first 18 years of my life. We’re always at odds with the world. MR: Things got a little tough when we went to college in different states, but we kept writing. I went back a couple of times, and we saw each other when I came home during school breaks.
AK: But then we had a long period of no contact. I came out to Madeleine when I was 21 and she was wonderful. But I had some bad experiences in heterosexual settings, and because of that, I found myself involved in the gay community in New York from my late 20s into my 30s. We didn’t keep in touch during that time.
MR: I made other friends. I wasn’t mad at him; I just thought we went our separate ways. And then one day, out of the blue, Amy emailed me.
AK: There’s no good answer to the question of why it took me so long to do this. I ended up doing this because I was with my family for Thanksgiving and my cousin asked me about Madeleine. The phone rang right after I sent the email and it was Madeleine. At the time, I had no idea that emails moved so fast!
MR: The day we met again for lunch, I remember crying. It seemed like a waste of time because we hit it again right away. After that, he never stopped.
AK: In many ways, We are very different: I am a fan of sports and physical activities and Madeleine is not a fan of it. But there is a level of unconditional trust and acceptance that is at the heart of it all. I know I can tell Madeleine anything and if she doesn’t agree, I won’t judge her for a second. Whenever something really good or really bad happens in my life, I want to tell Madeleine right away. She understands me. If I think I’m funny, she does too.
MR: I feel the same way. I would have said the same thing about him! I’ve also had a lot of health issues over the years, and Amy has been there every step of the way. She’s my go-to, in addition to my son. I know she wouldn’t get tired of seeing me sick. She’s very supportive.
AK: We’re very clear about how important we are to each other. We often say, “I love you.” We’ve expressed that we’ll be there for each other forever, and at our age, that’s extremely comforting.
Another The advice I gave my daughter is this: “Recognize that all my friends, no matter what the day, are idiots. “That means I don’t like everything they do, but I still like them.”
MR: I told my son, “You can have friends for different reasons.” Not all of my friends want to do everything I want to do. For a while, I felt like I needed to be around everyone as much as possible. Then I realized: “No, I don’t.” But with Amy, I don’t have these problems.
