There is no doubt that proximity is one of the greatest initiators of friendship. As children, we are in classrooms, teams, camps, clubs and on playgrounds. Our selection of friends is typically within arms reach at any given time in our young lives. Those who are around us day in and day out become familiar, comfortable and typically our best friends. When you head off to college as a young adult, you are once again living and working closely with your peers who become the pool of individuals from which you will select your friends.

Rebecca Adam, professor of psychology and gerontology at the University of North Carolina at Greensboro, describes what sociologists in the 1950’s determined to be the three necessary conditions that are critical to forming close friendships: proximity; repeated, unplanned interactions; and an environment that supports people letting their guard down. This is why so many friendships are formed in school either early on or in college.

As we get older, and unless we are in an isolative job, we are still surrounded by others at work or in various social activities but the game changes. People move or change jobs and time moves much faster than when we are kids. We also tend to be a bit more discriminating about who we chose to spend our limited amount of free time with. Kids bond over things such as wearing the same sneakers or liking the same sport and very little else is required to initiate a bond. Most adults need to feel some sort of connection emotionally and or intellectually to spark a relationship. Maintaining that relationship can be even more challenging.

Once spouses and then children enter the picture the plot thickens. Now there are new personalities and schedules to deal with that can sometimes interfere with what previously seemed like a close relationship. Time constraints become a huge deterrent when it comes to keeping continuity with friends. Of course a spouse and children bring with them a fresh batch of people that you may call “friends” at some point. Those parental friendships can become lifetime ones but often they are subject to the whims of your children. If the relationship was built around play dates and family outings together, when that phase passes, so too can the friendship.

Laura Cartensen, a professor of Psychology at Stanford University, commented that as people moved towards middle age they tended to interact with less people, but they interact more frequently with their current friends. In other words, their social circle grew smaller but more cohesive. Cartensen suggests that big life events, such as turning 30, are make people more aware of their mortality and time limitations so they become more focused on the present and those things that are emotionally important to them at the moment. People become more interested in spending time with their family then say, going to party.

The irony is that as we age we need those friendships even more. It becomes harder, although certainly not impossible, to pick up and start over someplace new with a new cast of characters. A key factor in maintaining happiness is feeling connected and genuinely cared for by the people in your life. It may be that narrowing our focus when it comes to choosing friends later in life is a positive adaptive skill. Despite the added effort it takes to either maintain longstanding relationships or make new ones, I always encourage my clients to put in the time and energy necessary to do so. Friends add greatly to our quality of life.