Best friend relationship?

My best friends seems to have a new friend every single year. That usually lasts up to a year and when this friend comes along I have to chill with them even if I don’t want to because they’ll always be around her. Tbh to an extent I even feel like she’s rather be with them than with me. I don’t have any other friends and she knows this so I think in her head she looks at me and knows I won’t go anywhere I have no other friends so I’ll be waiting for her at the end of the day when the friendship is done. And when she’s no longer friends with this person she because so clingy towards me and the circle repeats it’s been like this for four years now. I had found her with a best friend when we became close and she did the same to her.
What is your take on this?
Best friend relationship?
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