Why would my boyfriend's friend and his girlfriend unfollow me on Instagram for no reason but the guy watches my stories still?

Her boyfriend (boyfriend's friend) watches my stories still but unfollowed me for no reason even though in real life he talks to me and is sweet. It never seemed like he didn't like me. Every single other friend of my boyfriend follows me... It's kind of weird...

Why would my boyfriend's friend and his girlfriend unfollow me on Instagram for no reason but the guy watches my stories still?
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