That being said, I am a big believer in long term friendships, but like all really good friendships, there's an element of luck. But even good friendships can fizzle out.
Be honest and reach out and people will either match your energy or they won't.
You just give it your best and know that you did what you could. Which from what you said it sounds like you do. If they are telling you they don't want to talk anymore, than that's unfortunately beyond your control.
You'll find your people and they will work with you to make the friendship last. You just have to keep meeting people and being open. Life is always moving.
I've lost a lot of friends in a whole range of painful and benign ways and it never gets any more fun but eventually other doors open. Sometimes it's lonely, but it's a feeling everyone goes through.