Hey...I've been reading your story, and I just have some advice to make it a little better.

1) Make your story deeper.  Develop the characters over time.
2) Describe the setting. Let us feel what the character's feel. I don't even know what Jen looks like.

3) The whole sex thing went to fast. You should have made it slower, not rush into it. Make the moment special, because obviously, this is a special moment for Jen and Justin.

That's some advice. If you have any questions let me know. I'll be glad to help :]