I'm going to be the optimistic one and say that I've known a bunch of horses that just click with certain people. I really like the Morgan, and I'm going to hope for the best all the way--that the new friend turns into a true friend, and that you have lots of great adventures training him, and was meant to be that nurse's horse.
I gotten horses that were terrible for other people but just fine for the person who ended up with them. Last week I went with my neighbor to look at a horse, and the horse acted really badly. The seller was mystified and said, "She never has done any of that." I believe that horse just didn't want that man to buy her.
That same man had a horse, appropriately named Angel, that he sold to an extremely experienced, kind, easy riding friend. She buys kill pen horses as a hobby, gets them going nicely, and sells them to people that want them. She loses money on just about every sale, but it gives her pleasure to find good homes for good horses. So, she bought Angel, and the day we took her to that farm, Angel was horrible. Nobody could ride her. They kept her for two months, and she did all kinds of terrible things. We went and picked her up and she was fire breathing dragon.
We took her back for someone here on Horse Forum to try her for a week, and she was lovely. Never had a moment's problem with her. That person ended up not buying her, but someone else on Horse Forum bought her and used her for riding lessons. There was something about that friend's farm or something about her that Angel just didn't want to be there.
I think if it's meant to be, the horse will tell you. But until then, I am going to be excited for you. The Morgan is lovely and the new nurse friend might be just the one!