"There you go, baby, just get in a comfortable position above me."
"Like this?" You say as you climb on top of her, shaking as you try to line your penis up with her vagina.
"Yes, OH GOD, BABY, I can't wait to feel you inside me..."
"Now what do I do?" You ask as your cock twitches uncontrollably.
"Put your tip right here in front, and just thrust it inside."
"I... I need your help."
"You can do it," Christy encourages. You manage to get your dick close to her pussy. This is the closest you've ever had to sex before, you feel the tip of your cock actually touch the outside of her vagina. You can feel a few of her pubic hairs tickle the head of your penis, and it is at this point that you know you're going to fail again. "Come on, baby, you're so close. Just thrust it inside..."
You try to obey Christy. You thrust, but you don't actually make it inside Christy's vagina. You slip over it, and your dick slides up her belly. Just from this slight friction alone you know you are going to nut. Realizing it is pointless to try to make another attempt at penetration, you give in to your fate and admit to Christy, "I'm gonna cum!"
"Wait," she says in bewilderment, "You're not even in yet..."