Hello micheleispoly,
Two years ago, when the two of you decided to open your relationship, did you both assume you would only be dating other women (not men)? Was this said out loud at the time? or did you figure that dating men was okay, but you assumed neither of you would get pregnant? Was this said out loud at the time?
I get the impression that you don't feel threatened by her dating women, like you do by her dating men. Is this something elemental about men per se, or is it specifically because men can get your partner pregnant? or would pregnancy be okay, as long as she wasn't romantically involved with the father? or is it a combination of all of the above?
You seem to be afraid that with that level of involvement with a man, that your partner will break up with you. Have you expressed this fear to your partner? and if so, how did your partner respond? What did she say? Do you believe her? Do you trust her? Do you trust the solidity of her commitment to you?
Maybe you're afraid because mainstream society holds that a man and a woman, with a child together, are the ideal foundation of a happy family life. And maybe you're afraid because mainstream society holds that a woman and a woman, are a recipe for unhappiness in life. So maybe this is a fear that your partner will succumb to the pressures of mainstream society, once she experiences firsthand the joys of having a child with a loving man. In the back of your mind maybe you've always been afraid of the influence of mainstream society. You've always been vulnerable to that influence due to your two-women relationship.
And even if she doesn't break up with you, maybe she'll demote you to secondary partner, and the man will become her primary partner. Is that a fear you have? What if she decides she still wants you to be primary to her, but she wants the man to be primary to her as well? Could she have two primaries? Is that something you could live with?
Describe if you can and if you're willing, exactly what you're afraid will happen and why. What parts of your partner's proposition frighten you, and why? What's the worst possible outcome? Would you be happy in the role of second mother to this child? Why or why not? Your answers will help me help you.
Sincerely,
Kevin T.