Would I be wrong to move on from my coach?

This is going to be a bit of a long winded post, so I apologize in advance.

I have been riding for 17 years, owned my own horses for 10+. I switched from jumpers to barrel racing in my teens and never looked back. Never really took any lessons and was mostly self taught until I bought a baby and started training him. He proved to be more of a challenge than I expected and is constantly pushing me to expand my knowledge. My current “coach” is actually my long distance best friend. For some context, this is not a traditional coaching situation; I send her videos and she dissects them and gives me things to work on in my next session. This has worked extremely well for me, as I was in a bit of a sticky financial position for the last couple years, and this was an inexpensive solution to my not being able to afford a traditional lesson program. I love my coach, and she is like a best friend, but I have recently been pursuing studies in equine welfare as well as pushing myself to become a better horseman, and I’m starting to see that she may not be as knowledgeable as I first thought she was.

For example, she has a horse for training that she has been working with for a couple months now. She claims the mare has learned she can buck and get away with it, but every video I see of this mare she is giving constant pain signals, and my coach will not listen to anyone when this is brought up, she’s “just a mare”. Morally and ethically, I don’t know if I can continue with her so long as I am also continuing on this journey to better myself as a horseman, but she is still my friend and I do not want to upset her.

I guess what I’m wondering is;

1. How can I bring this up to her in a way that isn’t super confrontational? I value her as a friend but I would really like to take the opportunity to share my knowledge on equine behaviour and help her understand why this mare might be acting out

2. Would I be wrong to move onto a new coach after my friend helped me when I was financially struggling?

Thank you in advance:)