Hi, you need to have foreplay at least for half hour to one hour till you feel orgasmic. If you can't have orgasm properly, then it will be always painful. Try some different tricks and you can use toys/Gels/ creams available OTC at medicals.
First of all are you married or unmarried?
If unmarried, the sex is often hurried and due to this the arousal is NOT proper.
Even if you are married then the reasons for painful sex could be ......lack of foreplay....lack of arousal....fear of being found out.......fear of pregnancy.......lack of proper technique of relaxation.....uncooperative rough partner.....lack of lubrication.....and even some medical problems like pelvic inflammatory disease, vaginitis., ovarian cysts, vaginismus, endometriosis etc
This results in very less lubrication and the fear of pain may also contract the muscles around the vagina to cause more pain....
If lack of lubrication if the problem, then it can be helped with lubricants bought from chemists shop.......
Learning to relax at sex is the most important aspect......DO NOT Hurry...ask your partner to be gentle and caring.
A examination by a gynecologist may be needed if the problems are to be ruled out.
If you are married, frequency of sex can be increased to help get accustomed to the act and to learn to relax and be gentle by both of you.
If you are NOT married, I would suggest you to either abstain froms ex or use a proper contraceptive like oral contraceptive pills AND condoms to protect you from sexualy transmitted diseases and also pregnancy
To get aroused, you may do clitoral massage to get sexual pleasure or make the partner do it at foreplay to help relaxation and lubrication