https://www.webmd.com/sexual-conditi...n-during-sex#1
In some cases, a woman can experience painful sex if one of the following conditions is present:
Vaginismus. This is a common condition. It involves an involuntary spasm in the vaginal muscles, sometimes caused by fear of being hurt.
Vaginal infections. These conditions are common and include yeast infections.
Problems with the cervix (opening to the uterus). In this case, the penis can reach the cervix at maximum penetration. So problems with the cervix (such as infections) can cause pain during deep penetration.
Problems with the uterus. These problems may include fibroids that can cause deep intercourse pain.
Endometriosis. This is a condition in which the tissue similar to that which lines the uterus grows outside the uterus.
Problems with the ovaries. Problems might include cysts on the ovaries.
Pelvic inflammatory disease (PID). With PID, the tissues deep inside become badly inflamed and the pressure of intercourse causes deep pain.
Ectopic pregnancy. This is a pregnancy in which a fertilized egg develops outside the uterus.
Menopause. With menopause, the vaginal lining can lose its normal moisture and become dry.
Intercourse too soon after surgery or childbirth.
Sexually transmitted diseases. These may include genital warts, herpes sores, or other STDs.
Injury to the vulva or vagina. These injuries may include a tear from childbirth or from a cut (episiotomy) made in the area of skin between the vagina and anus during labor.
Vulvodynia. This refers to chronic pain that affects a woman's external sexual organs -- collectively called the vulva -- including the labia, clitoris, and vaginal opening. It may occur in just one spot, or affect different areas from one time to the next. Doctors don't know what causes it, and there is no known cure. But self-care combined with medical treatments can help bring relief.