Hormonal changes: After menopause, painful intercourse is associated with decreased estrogen levels. The vaginal tissues tend to become less elastic, more fragile, and more susceptible to bleeding, tearing or pain during sex or during a pelvic exam. For many women, vaginal atrophy shrinks the vagina making intercourse painful or impossible.
Vaginal pH imbalance: The loss of oestrogen causes the vagina to become less acidic, which makes the body more susceptible to urinary tract infections (UTI's) and pathogenic bacteria. Vaginal infections can cause dryness, and itchiness which also can make sex uncomfortable.
Pelvic muscle tension: Pain associated with deep penetration or certain positions may be caused by inadequate relaxation of pelvic muscles or conditions that affect the pelvic area, such as pelvic floor dysfunction, endometriosis and uterine fibroids.
Other factors: Sometimes, other factors are at play, including injury or trauma, such as from childbirth, or pelvic surgery (prolapse, preventive BRCA related, ovarian cysts among others) . Skin conditions like eczema or lichen sclerosus, or an infection in your genital area or urinary tract also can cause sex to be painful.