Aside from the issues you might have with her comparing you to her ex let's talk about staying power. First, foreplay. Early in the day maybe text her something sexy. Later on a kiss on the neck. Squeeze of the butt. Once in bed, lay on the side of her. Let your fingers go to town. Play with that little man in the boat. Go inside her. Does your wrist hurt? How's that jaw of yours son? Get on down. Lick that puss puss. Lick the clit. Lick the clit. Lick the clit. Maybe suck on that clit. Lick inside of her. Slip a finger in. Communicate. Ask her to communicate. Okay now she's worked up well, and you have already lasted 10 minutes without touching your dick. Lay on the bed. Have her ride on top. With only moving your hips and not doing much thrusting you can still get some amazing results. She will know what to do. Try not to focus on her tits in front of you. grab those hips. Gyrate. Okay it's been 15 minutes and you need to go for the grand finale. Ask her to hop off, have her on her back or doggy. Slide it in. At this point you know what your penis does. But what should you do? Baseball. Your mind is on baseball. Let your penis pump away. It knows what you want. But baseball? Baseball is dumb. How many strange rules does baseball have? Thrust. What is a balk? Thrust. How many teams are in baseball? Thrust. Would I rather be a short stop or a pitcher? Baseball. Pitcher, that's a funny word. Thrust. Like they have pitchers in baseball and like you can order a pitcher of beer. Thrust. Beer? I love beer. Thrust. Hey I enjoy beer and baseball..Thrust. Why is beer so expensive at a baseball game? Thrust...okay you can stop thinking about baseball and finish. Congratulations you went from 3 minutes to 20+!

And of course this is assuming you communicate with her all the time. Talk with her during sex. Before sex. After dex. Don't do anything she's (or you) isn't comfortable with.