It sounds to me like she needs to accept that people do indeed get hurt, especially when they make themselves vulnerable to another in a relationship. But they also heal, and the point now is where she wants to be while healing is happening and when it's finished.
If she truly wants to keep her relationship with you, she needs to let go of the idea of a deadline, period. If he's not a cowboy (someone who tries to split up an already existing couple) and truly is interested in a relationship with her, he can wait. They can wait. The utopia they may be envisioning could be possible- I'll pretty much have mine in June once my partner moves to the same city as my husband and myself- but it takes TIME. My husband and I have been slowly making the journey from open relationship to poly for FOURTEEN YEARS. TGIB and I have been on our journey together for over two years. Fast can work, such as in Phy's situation, but most of what I've seen shows that making poly work, especially starting with an already established monogamous relationship, takes honesty and communication (duh) and TIME. If she's not willing to give the time, then it seems to me she's not really interested in making poly work.
Reading "The Ethical Slut" is a good step, though. Hopefully now that you know about it you can benefit from it as well.
Pan Female, Hinge in a V between my mono (straight) husband, Monochrome and my poly (pan) partner, ThatGuyInBlack