When writing a story, how far can two people in a relationship go without the rating going over Teen?

I'm writing a story on a site and do not want to get into trouble for posting something as Teen when it really should be in Mature. So how far can two people go (ex. , dry ...) before it crosses over into Mature? Can you actually have two people "doing the deed" and still be in Teen, just don't be very graphic? Any feedback would be great, thanks!