Pull her on top of you.

You lie back on the couch and remove your underwear, while Sarah provocatively removes her lingerie. The black silk garment floats to the ground carelessly, and Sarah eyes your throbbing cock. She licks her lips again, and starts to move her head towards it. Before she begins, though you stop her, pulling her on top of you.

While never one to give up a good blowjob (and Sarah is fantastic), your girlfriend specifically asked to be fucked. And you're a nice guy. You decide to go along with it.

Sarah smiles as she straddles your hips and lowers herself down onto you. Within moments, you are embedded to the hilt in your girlfriend. Her breathing quickens immediately, and she rocks back and forth slowly, beginning some gentle friction. She reaches down to fondle your balls as she begins pushing herself up and down. You meet her slow thrusts with your own, driving yourself incredibly deep.

The pace slowly quickens, and soon you find both you and Sarah covered in sweat. Sarah begins whimpering as she becomes impatient, and soon she is bouncing up and down like a possessed woman. She switches her hands occasionally, always tickling and scraping your balls with her nails.

"I'm gonna cum soon," she gasps, bouncing even faster. You nod, unable to say a word. The constant stimulation has dried your mouth and taken away most of your coherent thought.

She begins to tremble, a sign you know signifies an imminent orgasm. "Cum with me," she whispers. "Cum inside of me."

You know you can hold out, but she seems rather intent on getting off. Do you hold on, give her a few more orgasms, or do you let this one go?