From what you've written, particularly your last post, it seems to me like this pattern isn't so much about the young women as maybe about trying to reclaim the young years you feel you didn't live fully?

This may be a form of grieving you are going through, grief over your younger years and regrets. I think this can only be resolved within yourself, when you can have peace and self compassion for the life you have lived and the choices you made.

In terms of this woman, it sounds like she regards you as a friend, maybe a bit drastic to unfriend her but if you 'unfollow' her posts won't show in your news feed and she will be none the wiser. Personally I would be grateful for the friendship you have with her.