Thank you for your question
Pain in the lower abdomen during or after intercourse originates from the deeper pelvic organs. There can be several causes. Infection is one of the commonest which needs treating. This can be in the urinary bladder or the pelvic organs themselves or both. Your partner needs to be examined by a gynaecologist and also probably have an ultrasound examination. If an infection is suspected it is often customary to treat both partners so you may also be given treatment.
Your gynaecologist will be able to rule out other causes in case an infection is not the cause.