Is it normal to grow apart after high school and college years?

Yes, it is very normal to grow apart. We all are learning & growing & everyone's interests change. They change. I change. I'm actually best friends with a gal I went to school with and never associated with or didn't feel apart of her circle and then 25 years later we develop a friendship. The best friends I had then I don't consider my best friends now, although they are on facebook, as are a lot of my class mates. People have always come and gone & I've learned that is just life, but it doesn't mean not to give your all while they are in your life. I've unfriended people just because and people have done the same to me. Just live your life. Be true to you and carry on.