Making love is important at some point of the relationship.
Guys wanna see how committed is the gf.
Girls who loves bf must sometimes give in, although not all of the time. If you don't want to, just tell the guy, and hopefully he'll respect ur decision. If u waited too long, then might as well break-up and find a priest(if you do read newspaper, they have an even higher sex drive).

It is a very important element in the relationship. Cut it with the saving for marriage. Do u want to save ur relationship? Especially when a gal who had many times and suddenly said that she don't want to have it no more. Be honest and tell the main reason, whatever it might be! (STDs,painful,etc) Although what I say may not apply to everyone, believe me, it's going against the nature if you don't have it.