Maybe I have an unpopular opinion, but hear me out.
As you grow older, you tend to deviate away from your friends quite easily. At one point you understand that you have different interests, hobbies, loved ones to take care of etc. The list is very long. Remember that time in high school that you vowed to your best friend you'd stay friends forever? If you're one the 0.00009% of people, congratulations [1]! If not, I'm sorry, but I get it, I really do.
As you grow older, you begin to realise that the essence of friendship isn't whenever someone gives you a piece of their candy or says "good morning" to you every single morning. You really begin to understand the spiritual level of a friendship between two (or more) people. You need to connect with each other, you should feel comfortable with each other and they should have the time to listen to you when things aren't going as great as you would like.
And yet, one day, you also understand that some people aren't your friends, per se. They are just acquintances that seldom write to you, ask you how you're doing (not out of curiosity, but out of courtesy) and that is the end of the conversation.
Or you may have one of those friends who keep asking for your help, which makes you feel special – you can offer them the help they need – but whenever you're in need, they are not there. They always have something more important to do or another way to spend their time.
I miss genuine friendship. If you have a genuine friendly relationship with someone, cherish it.
[1] https://www.sidmartinbio.org/what-percentage-of-friends-stay-friends-after-high-school/