When you look in the mirror what do you see? Do you see someone who is strong, weak, indecisive ? Do you see someone who understands horses, or someone who thinks they understand horses but really does not understand them at all. Years ago everyone had horses for transportation, so you either got a good horse and paid more money for it or got a cheap one that most likely had some issues and learned how to make it better. Otherwise you had no transportation except to walk on your own two feet. Therefore there was more incentive to understand and to train horses and you felt lucky to own one. 

Now they are for pleasure and now there are many more problem horses or should I say problem people. 

I tell every horse buyer, it will take you a year to understand your horse, but it will only take your horse minutes to know who you are. They will test you and read all your weaknesses and strengths in minutes and they will use that to their advantage before you even know it is happening. If you are weak, they will lead you around and they will not trust you when they are fearful. They will turn and run until they feel safe. If you are strong they will follow you and trust you when they are fearful. They will try to do what you want as they feel safe being with you and they want to feel safe. That is why the horses get better with good trainers. 

Instead of getting mad at your horse or blaming the trainer or whoever sold you the horse when he does something you do not like, and instead of saying he is a bad horse, or it's because it's a mare, try to realize he or she is telling you about yourself, but it is up to you to look in that mirror and recognize what that is and to try and change yourself and horse's behavior for the better.