Yoga student in teachers training

I'm practicing yoga for almost 9 years and recently I started Vinyasa teachers training (300 RYT).
A few years ago, I introduced my Best friend to yoga and always motivated her to join yoga classes with me. Just before I started the training we talked about how I will teach her and practice on her in my teaching. She hasn't practiced for a few months until I invited her to practice with me. It was okay, my first time of teaching someone and I still gain knowledge, but since then she was avoiding invitation or disrespect my time, didn't come and didn't mention anything, and started to practice again in some other vinyasa studio (which she have never practiced before). I wonder why is that if there is something uncomfortable in going to a friend’s class? Is this derived out of ego? I was never intended to take money from her and it was clear, so she could only gain from it, both of us. My other friends are happy when I invite them. I am letting go of this idea but I still wonder. I'd be happy to hear some similar thoughts or experiences.
Thank you