I meant talk to her as your metamour that HE is dating. So you can feel emotionally safe he's not out with a nutjob.
Not as her being your own dating potential. If you are coveting the dating experience he is building with her, that is envy.
Wanting what he has for yourself.
Going for the same people he is dating ADDS or TAKES AWAY from the rocky problems between you? I would think it would ADD, so she's just automatically on your "do not approach" list for the sake of the relationship you are building with him at this point. It seems too new to be having the same dating partners when you don't know how (you + him) work yet.
I don't know if either of these could help you: