It’s got to be really disheartening if even your best riding companion won’t go out with you if Romeo is involved. I hope you can get this under control. Meanwhile, remember that he can’t buck with his head up, so the minute he starts to spook, lift his head as much as you can. It might seem counterproductive in mid-spook when he’s already sort of wild-eyed and crazy, but if you let him get that head down between his front legs, he’s below the bit and you’ve lost the ability to control him. Turn him sharply to either side. That, too, will prevent him from getting into position as he can’t buck with his neck bent. If you do the one-rein stop training as suggested above, that would also include strong sideways flexing of his neck.
Give it time! And if you start feeling down on yourself, I recommend the book Healing Shine: A Spiritual Assignment by Michael Johnson. That single book did more for me in solving pretty much all of my horse-related problems than any other of the hundred or so I’ve read. I got the audio version as I like to listen in the car.
Horses In the Yard