Why the best friend of my ex still follows me and still sees my social media stories?

When my ex and I started dating, his best friend and I follow each other, but it's been 2 months since my ex and I broke up and his best friend still follows me/friends with me in social media and still watches all of my IG stories. While my ex unfollow me and unfriended me for a month now. So why is that?
Why the best friend of my ex still follows me and still sees my social media stories?
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