Crossing her boundaries
If you cross a line, such as trying anal without asking and waiting for her consent, be prepared for her refusal and maybe her hasty exit. Trust is the biggest issue. She is vulnerable during sex and trusts you to value her boundaries. If you find that you have made some blatant transgression, don't make a huge deal out of it or move your hands or position to a completely new spot. Just stop the offending action in a smooth transition to another more pleasurable activity for her.
Finishing too soon
If it's been a while, don't let her know. She'll know enough when you secretly make her "one-minute man" list. Though it would be perfect sex to make her experience shattering multiple orgasms that have her screaming in pleasure, it may have felt too damn good for you to hold back. Coming quickly isn't something you want to do all the time, but when you do, don't apologize. Instead, play on her vanity as an exceptionally sexy woman -- one that made you lose all control. Say something like, "Wow, you are too hot, I just couldn't hold it in any longer." This way, she'll take your premature ejaculation as a compliment whereas, if you apologize, she'll see it as a flaw. To make up for your quickie performance, give her the best oral of her life until you regain your upright stature.
Taking too long
Here's the opposite of the above problem. Some men, like some women, take a little too long to orgasm. Women may feel numb—and even sore—after a while of continual pounding, and men may feel like a robot. A great solution would be to discontinue the action under an acceptable guise such as a bathroom break. When you return, it will be easier for both parties to move on from there. If she feels guilty about you not getting yours, let her know she can get you back at any opportunity.