What's wrong with me?

I've been with my SO for 5 years and we have his daughter every other week. I STILL don't feel a bond with her. I still don't feel like we have a relarionship at all. No matter how hard I try, it's just not happening.

Keep in mind though, she plays us agaisnt eachother. She pushes the boundaries way more then I've ever seen a child her age push (I have children of my own). As bad as this may sound, she carries on like an entilted brat 99.9% of the time. Even more so when my SO is at work. Like, I cannot deal, but at the same time, I can't give her everything she wants and let her get away with stuff that I wouldn't let my biological children do.

Life is so peaceful when she's at her moms, and when she comes back it's like hell froze over.

Tips? Tricks? Help?! I am at a loss. 🤦‍♀️

It's been FIVE years, she should be used to the transition by now. She's 10. 😭