Be a hole-monogomist.

You're definitely tempted by her ass, but her pussy was too amazing to pass up. You stick with it, thrusting hard into it again. She groans as you pump and reach around her to grab her big tits. You pinch and roll her nipples, and you feel a warm fluid spray on your balls and legs. You beam with pride. It's not everyone who can make a ninja cum.

Unfortnately (?), her orgasm made her pussy to pleasurable to hold off cumming any more.

"I'm cumming..."you growl in her ear.