TAKING RESPONSIBILITY
So much is averted and avoided by not taking responsibility for yourself/actions. People love to take responsibility for all the good things or even things that sound bad that actually make you look good. So and so abused this horse and it's _____ so I'm having trouble trying to fix it. This horse ______ so it threw me off because _______. (blah, blah)

Now, I'm not saying that this stuff isn't true or doesn't happen. But, let's analyze the difference between the following two sentences.
1. My horse threw me off.
2. I fell off.

Yep, in both cases you hit the ground and it probably didn't feel so great for any number of reasons. But, if the fact is that your horse did what you said, i.e. stopped really short because you yanked back on the reins in your own panic, and you flew over his head because you were up and out of the saddle, the horse didn't throw you off.

You fell off.

But, "I fell off" sounds so much worse, doesn't it? Saying my horse threw me off retains your ego and sadly, frequently allows you to not get your skills better because, after all, it's not your fault!
I'm not trying to crush anyone's ego, here. I'm trying to help you get better and if you don't think it's your fault, you won't be in a hurry to fix it. You fell off. SO WHAT!
The only real "so what" is that you are looking at it from a viewpoint that will not benefit you. Really! You will not benefit from telling yourself you're better than you are and it was your horse's fault. This story spin is easy. The truth? Difficult. But, that doesn't change the reality of the situation. If you can say to just yourself, "I fell off" you're on your way to fixing it.
There are so many different situations and causes for the various ways we end up on the ground, but analyze truthfully or ask someone who was watching what they saw, to see if your idea of what happened is in line with an outside view. It happens so fast sometimes and skills and perception get out of whack. Ponder, will it really kill you to admit, even just to yourself, that you fell off? If there was someone watching that knows horses, they'll know anyway that you fell off and didn't get thrown off, so... Don't go looking for corroboration. Hopefully, that someone watching can give you a more accurate account of what happened so that you can work on fixing it. If you don't believe you have anything to fix because it wasn't you... ? I'm not even saying that you're not trying to fix things every time you get on. I'm sure you are. However, be/get more precise with your assessment of yourself and horse so that you can precisely focus on the points that will help you stay on top. There is an art to riding ( The Art of Riding, Book 5, sadly well away in publishing time but started) well. It's not just staying on.

Bucking may or may not be a different story. If the horse was bucking because that's what he does for whatever reason and you can't stay on, it still doesn't necessarily mean he threw you. If the horse really wants you off his back that's a different story and we're not talking about that here.