What Is The Cause And Treatment For Painful Intercourse?

i have been trying to have sex for about 3 years now with the same person, I m 18, but i cannot seem to get his penis into my vagina without intense pain while trying, even with lube. we do have foreplay before and he can only get one finger in my without pain. I ve never worn a tampon before and I m nervous that ill never be able to have sex, please help!