Also, there is a difference between being demanding and consistent, and being mean. Women have a lot of trouble with this, usually (no, not all women, but women do have a bigger problem with this than men do).
Figure out what you want from your guy, communicate the expectations clearly, and deliver feedback to him on a very consistent basis. If he's doing it right, let him know. If he's not, let him know that. Don't let your standards slide. This is "consistent", not "mean".
A big part of this is not taking it personally when he misbehaves. It doesn't mean anything at all about *you*, so there's nothing to get mad about, but it is something you need to correct. Remember: It may be at you, but it is definitely not ABOUT you.
In this way, as far as I can tell, horses are just like kids...got to provide very consistent feedback and firm boundaries to both, very important not to take anything they do personally...