Hassanb,
Yes, by giving up something very important to you. I am the original author of this post. I am still with the woman I originally wrote this about, and I love her very much.
The choice you have to make is whether or not you can live with shutting out the little part of you that wants to die when you see the things you're talking about. People who have grown up understanding this kind of lifestyle have a marked advantage over those of us who have been blindsided by it.
I love my girlfriend more than anything except my children. So I shut that little part out.
Now, what IS wrong is that (assuming you have shared your discomfort at the things she says) your girlfriend shares those kind of things with you. I have been there before and I know just the feeling: frustration, helplessness, even rage. She shouldn't be telling you those kinds of things. But at some point you have to decide if you're going to trust her.
This might not help but I hope it does...as a man you must know how beautiful and sexual women can be. You might as well give up competing with that right now. But just because your girlfriend is aroused or attracted to the idea of being with a woman, well, it's not as big a deal to her as it is to you. You know why? Because she's WITH YOU. She's not with another dude, and she hasn't left you for a woman. You have something that only you can give her, and she recognizes that.
Be wary of co-dependency. Even for a reasonably secure man, being involved in a bisexual relationship is just opening the door to emasculation. The key is to become more confident in yourself. Unless she is just using you, recognize that she is with you because she loves you. I know one thing that has crossed your mind already is "how f***ing greedy do you have to be to want a man AND a woman?" Well, the likelihood is that you will not be able to change her mind with logic like that (that's how we men solve problems, right?).
It takes a strong man to be in this kind of relationship (if he actually cares about his woman and is not just having some kind of sexual adventure), even if the woman doesn't realize it. Stay strong.