Old friends

So there’s this guy in my English class who I knew when we were younger and I know he doesn’t remember me but I’m so disappointed, I wish he did. We were friends like 3/4 years ago but I feel sad about it because I really had hoped he did because we could’ve been friends again and maybe so could my sister with his twin sisters since they were friends before too. I feel really sad about it. I feel like I’m not allowed to feel upset because it was a long time ago.