We’re human, and we’re changing every minute. We never experience the same thing the same exact way more than once. Something is always different about it, whether it’s the weather, the time of day, or what thoughts are going through your head at that moment. Either way, it’s different. And it’s different because you’re different. You’re an evolving human being. You’re constantly seeing new things and having new experiences every day, it would be impossible to stay the same exact person for the rest of your life. You may like one thing one day and despise it the next. You may tell yourself you would never do something, and find yourself doing that exact thing on a daily basis a week later. You don’t have to feel bad about that. You don’t have to defend yourself and explain to others why you’re now suddenly going against what you used to say, because if you’re not changing, you’re not living, and you don't owe anyone an explanation for your life anyway.
As your thoughts and feelings and likes and dislikes are constantly changing, so are everyone else’s. Something that used to be the glue that held you and a friend together may just not be there anymore. You’ll go down one path while your friend goes down another, and soon you’ll find yourself forgetting when the last time was that you even spoke to each other. You can’t dwell on it though; you have to let it be. We’re all on different journeys in search of different things, and sometimes your path will no longer cross your friend’s path. It’s inevitable. People grow, their personalities change, and you lose connections you used to have with others. You'll start to find that your interests no longer align with one another's. The differences between you two will start to outweigh the similarities, and you'll eventually realize that simply they're just not someone you want in your life anymore.
I hate to be the one to bring in a cliché quote, but honestly, what’s meant to be will find it’s way. As much as you’re sick of hearing that, it’s the one piece of advice that always seems to hold true. You may think you and your best friend were inseparable and would remain that way for the rest of your lives, but if that person is now no longer in your life, then that means they didn’t belong on your journey with you. They were there for some of it, to teach you things and be taught by you as well, but that was their only role they served in your life, and it’s okay to let them go.
Life will go on. You'll meet new people, make new friends, find your new soulmate. You'll be happy, and you'll be happy that you're surrounded by people who are helping you grow. People who accept you as the person you are in this moment, and not the person you used to be. It's okay to have some initial sadness, it's okay to reminisce on good memories with old friends, but it's also okay to move on without them and live your life for you.