Try to explain

"Ok, so, it's like this," you say, looking to Diana for encouragement. She nods encouragingly. Excellent. "It's like this, er- why did you stop?"

"I was listening," Grace responds, her hand having paused its ministrations.

"Ok, first lesson- it's like eating ice cream. You take one bite, you do not want to stop. So, if talking to you makes you stop, I'm not gonna wanna- ohh shit."

You must have had her at 'ice cream' because halfway through your sentence she laughed slightly and started stroking you again, a little more firmly this time.

"That's- a lot better, thank you," you say, and this time she continues as you speak, "Each time you stroke me, I feel a wave of pleasure, something between a massage, and eating ice cream, and seeing a sunset, and running a race, all rolled into one- only the pleasure goes from my penis, into my balls, and then my belly, and it spreads all around, often growing the faster or more firmly that you stroke me."

"That's so hard to imagine," she says, intrigued, continuing to grasp you. She speeds up slightly, to see your reaction, and you nod at her, pushing yourself into her hand slightly

"It's like a tension. The faster you go, the more the tension builds, but it feels good, and it feels intoxicating. Eventually if the tension builds enough, it breaks, and explodes into orgasm, which is a very pleasurable release. _Very _pleasurable."

"How can I tell how much tension is building?" Grace asks, watching your face closely as she speeds up. Noticing your mouth open slightly with pleasure, she begins adjusting her grip, this time closing more tightly around your cockhead as she tugs upwards. You give a grunt of pleasure and she quickly adapts, now tugging your cockhead every time. You feel the familiar clenching slowly start to build deep in your loins, as pleasure starts to fill your body.

"It's- sorry, I-- it's hard to talk."

Seeing you're having trouble with words, Diana steps in. "Notice that his eyes are not fully open anymore, and that he's having trouble speaking. Those are both indications that his pleasure is building. Also, he's breathing more rapidly, and his penis is getting darker as it fills with blood. He's grunting more, making noises as you stroke him, and he's even pushing himself into your hand."

"So he's getting close?" Grace seems excited at the idea, and start squeezing even more firmly as she pumps you. You realize suddenly that your cock is aimed right at her perfect, moist lips and it's almost more than you can take.