Why do people keep unfollowing me on Instagram after I follow them back?

Anonymous
This has been happening more frequently recently. I keep getting people, mainly girls, following me on Instagram and I usually follow back. However, when I go to check their following list after a few days I am no longer there.

I remember this one girl who followed me. She has 2 accounts. One for her social activities and one for her work/business activities. On both accounts she followed me first and so I followed her back. However, whilst I thought she was following me as well she stopped following me. Why would she follow me first and then unfollow me once I followed her back?
Why do people keep unfollowing me on Instagram after I follow them back?
3 Opinion