Why do people I know *in person* unfollow/ not folloe back om Instagram?

[I Should Be Sleeping]

I know it's immature to care but I'm really wondering. Like for example, one girl from school who was always really really nice to me in person and always said hey will never follow me back online. And another example is one girl I know, and friend of a friend, unfollowed me but before she would always comment nice things on my page.
I dont understand why ? Perhaps jealously/ envy and they dont wanna dee my posts maybe? I'm really bewildered...

[Sydney]

Not jealousy boo. They probably don't like you. From a personal experience, I unfollow people because their statuses, or pictures are annoying lol. Everyone I know who unfollows doesn't do it because they're jealous, the persons stupid posts are just annoying as fck. I follow people if and only if I care or I'm interesting about what's going on in their life, if I don't care, I don't want to see their face popping up in my feed lol.