Is it normal i still miss my best friend from high school?

Long story short: I was friends with a girl in high school, and I initially thought she had a crush on me, turned out she didn’t, but we were still friends, especially in our 10th grade English class. She and another of her friends were the best part of my day, but I was really sad when in 11th grade we didn’t have classes together, but I still saw her in the hallway and at the end of school once in a while and we still got along good.

But then I had a lunch hour with her the next semester, and things took a turn for the worse. She had a new team of friends who were some of the most annoying people I’ve ever met, and I realized something about people: that they act differently depending on the people they’re with. I really didn’t like the way she was acting around them, but I did like the way she acted when she was with me or her friend from 10th grade English.

Looking back, I just regret not doing more things with her outside of school. It may be hard to believe, but once she really was a good influence in my life, but I guess my mistake was assuming that things were always going to be that way. To this day I’ve never met anyone who made me feel as good as she did, and I’m reluctant to make friends, because it was the best friendship I ever had but it ended in disaster.