Wishy washy

Hey guys so I'm in a long distance relationship for almost two years now. I see him every month and it's great. I love him and we're getting really serious. I've had a past of insecurities but I met him and he's my first boyfriend. He makes me feel like a princess and I'm so spoiled☺️ He's my first everything. Literally. Now we're in college and now we're getting so serious, I'm getting really scared... I know I want him to be by my side when I grow old because he's honestly my best friend. But I have a tendency of changing my mind a lot. I just don't want to feel this way then next thing you know I wake up in 10 years and I'm like I don't want this... Nothing's wrong with him. He's perfect. I'm scared I'll be flakey... Can I get some advice? Im so just scared. I don't know... I love him but why am I freaking out?