Yup, I had one of those. I tried for 2 years to make a happy pair of the two of us, but it just wasn't happening. She left here a better horse than when she arrived. The new owner is having the same problems, but because she is spending more time with her things seem to be slowing improving. The horse and owner are quite happy. So am I because my headache is gone!
There will be a home somewhere, if as the trainer says, there is a good horse in there. A different owner, a different barn, more or less horses around. If you let your trainer know your intentions, (s)he can help find another home.
Then you can find the right horse for you. It's only fun if it's actually FUN!