I’m struggling with the thought that someone elses behaviour means nothing about me

Someone I became friends with suddenly lost interest in our friendship. I thought we had a great friendship, they even said to me once “I don’t know in what capacity but you are in my life forever now” and I really took that to heart.

Now we don’t see each other due to COVID. I feel sad and a bit bitter that we don’t even talk or message because it just feels like they dont want to talk to me. I got some coaching on this and I was told that their behaviour means nothing about me. I think I get it and then I think
“If i was better/funnier/prettier/more successful, they would totally still want to be my friend.” I am really finding it hard to think otherwise! My brain is telling me it is fact “if you were better of course you would still be friends and you would have more friends!”