She wants to experiment...

My partner is in her mid-twenties and feels she never had the time to be "wild" because she married young. She met me and then divorced her husband. We are planning to get married.

Now she has met some other people who believe relationships can be "open" because love can be displayed in many different forms and sex is merely physical. She is attracted to one of these individuals and is wanting to experiment with this new concept but won't because it hurts me. But I feel this won't die so easily...

Is my pain normal? What can I do to ease the pain? Do open relationships really work? How can I accept her being with another man?

Any help will be greatly appreciated.

Your pain is normal. I do not think you can accept your partner being with another man. Open relationships seldom work although it happens sometimes.