Whenever my fianc ejaculate inside me i feel a lot of discomfort 20 mins after. i get really bad stomach pains (cramps) i get very bloated.

Not sure: Not sure why this would happen. Could be gas introduced at the time of intercourse or could be coincidental. Is this with vaginal sex or anal? Would discuss with your GYN before you get married.

Prostaglandins?: One possible cause is the prostaglandins that are in Semen. Prostaglandins can cause uterine contractions that feel like cramps. (We use them to induce labor sometimes) This reaction can sometimes be blocked by taking Ibuprofen prior to having intercourse. Best wishes!

Try condom: As doctor Leighton pointed out, it could be due to introduction of air. However, if it has any thing to do with semen from your fiance, you could test that by having him use a condom and see if you still get the same symptoms. For good health - Have a diet rich in fresh vegetables, fruits, whole grains, milk and milk products, nuts, beans, legumes, lentils and small amounts of lean meats. Avoid saturated fats. Drink enough water daily, so that your urine is mostly colorless. Exercise at least 150 minutes/week and increase the intensity of exercise gradually. Do not use tobacco, alcohol, weed or street drugs in any form. Practice safe sex, if you have sex. Get HPV vaccine.