OK... THIS is why intercourse is not stimulation:
The ****oris is the MAIN part of the female body that must be stimulated for the woman to achieve orgasm. Simple intercourse.... "f*cking"... does not do so, unless you really know what you're doing. Your **** is going in and out, but the ****oris is OUTSIDE the vagina and soes doesn't really get affected. It usually takes your fingers or your tongue to get at the ****oris.
Some girls get off from the guy getting at the "G spot", but this is a difficult objective. The "G spot" lies about 1 to 1 1/2 inches deep on the anterior of the vagina wall. You get get at it by putting your finger inside the girl's vagina and doing a "come hither" motion.
To be fair, though, and largely by my experience... a girl will NOT come unless you have made her comfortable enough beforehand. There's this crazy mental/physical connection between a woman and her *****.
But again... just for the youngsters out there.... it is VERY rare to be able to just f*ck a girl and have her come all over your wang. I know that all manner of popular fiction, film, and pornography has you thinking that all you have to do is throw yourself in there and pump away, and all of the sudden the girl will come all over the place, but that's not reality.
There's TONS of literature, much of it on the internet, about this already.
This isn't to say that girls don't like f*cking. They love it. It might not make them ***, but it certainly is the pinnacle of the male/female connection. Just having the guy feel good inside her is a great boost for so many women... just enjoy the ride, man.
Sorry if this seems pedantic. But a lot of young guys here are probably overestimating their sexual abilities.