“I want to be friends in high school. Let’s make plans to meet every month,” my then-best friend told me during the summer before high school as we walked to her house, sharing earbuds and cheerily marching to the music. We were bound for different high schools, and our friendship was soon to be broken.

Sadly, although we still stay in touch through occasional messages and Snapchats, my best friend from middle school and I now barely see each other and don’t maintain a constant friendship. Every time we meet — maybe a couple times a year — we promise to meet more often, but as our busy lives get in the way, we often forget to keep these promises.

Although I feel guilty about not maintaining my relationships, I’m not alone. According to evolutionary biologist Robert Dunbar, a human being can only maintain five intimate friends at a time. I’ve grown to realize the truth in Dunbar’s words. After changing school districts three times, I have found it more difficult to maintain real, close friendships with people I no longer regularly see in person.

When I attended Oak Avenue Elementary School in Los Altos, my best friend just happened to be my next-door neighbor, a girl who I had known since I was a toddler. My childhood was filled with sleepovers, birthday parties and daily walks to school with her, but when my parents decided to move to Saratoga when I was in the fifth grade, I could only promise her that we would stay friends.

After frequent email conversations, I remember inviting her over to my house when I was in sixth grade. I quickly found that gossip surrounding the people at my old school and “High School Musical” references no longer interested me.

Then came middle school. At St. Andrew’s Episcopal School, I befriended a girl who enjoyed running and English class as much as I did, and we went to the movies every Friday. But as the summer before high school arrived, my friends, who all planned to attend different high schools, seemed to be too busy to make time for each other, and after meeting a few times in the summer, we eventually stopped meeting altogether.

In fact, whenever we occasionally bump into each other such as at cross country meets, we smile and quickly catch up, but the conversation is flat and plastic — the promises to meet again are empty and little effort is put in carrying them through.

With the help of social media, I still keep in touch with many of my old friends, but it’s doubtful our relationships will ever go back to the way they were in the past despite our best intentions and promises to recreate what we had.