Chivalrous college girl vs. a guy with a delicate constitution (not literally, it's his personality).
The heroine is my treasure. I kiss her a hundred times every day.
There's something to be said for a delicate guy, too. Calm and collected, breathing evenly, he plays with his darling until she's barely got a breath left.
This is a story I've had finished on my hard drive for years. I'll post it once I get around to revising it. (I have no idea why I was so into writing delicate guys a few years ago... Just leave me alone.)
One-sentence pitch challenge:
A girl who talks tough, and a guy who seems mild and delicate but is actually at the peak of possessiveness.
Theme: Treasure the one you have.