My universe? Lies to me are a one strike you are out.
It would have to be pretty extenuating circumstances for me to slide on that. It is a hard limit for a reason. It would be on me and DH to use our playbook as a guide to help us discern where we stand if something came up to challenge that limit. But I have the right to end the relationship for a lie told. It's an agreed to limit! Whether or not I exercise that is up to me. NOT my DH. Because he would have been the liar that got caught out.
Because the OP is posting about it and not firmly calling it done? I tried to answer from his position, not from my personal life. The position of he still sounds like he is processing. He sounds like he wants to stay in it but needs help coming to grips with the whole problem/betrayal/forgive thing. (Be nice if they had taken the time to write out their own playbook to help them in these tough times though.)
So going from that position -- well, what can be done then? Is he willing to give her the second chance? That's on him to decide.
Over what ...A lie about what...... having pie with a guy she is dating and already sleeping... that makes absolutely no fucking sense. At least not to me
Makes no sense to me either. She can try to explain to her partner why. He's the only one who counts. He is the one weighing her in the balance and their relationship. To see what kind of return on his continued investment he can expect.
IF he is willing to give her the pass for previous good behaviour, NRE, first polyship, whatever she says it happened for?
They are reasons why she messed up. But reasons are NOT excuses for lack of truthiness. She can explain why she did a bad breaking of boundaries, but it is still a bad.
She still has to make good on her bad, IF he allows the second chance. But only he can answer IF he is willing to grant the second chance or not.
They are at a place of discernment for themselves.
If he gives it, he has to give it all the way. Not partially. He cannot hold it over her head all the time and punish her endlessly for the breaking of boundaries. If he plans to do that? For his OWN mental health it is better to cut the cord. Move HIM to a more healing space. Not continue the drain in a new shape. That is not a real second chance -- that would be holding them both emotionally hostage at this point in their timeline. Frozen.
If they go for the second chance -- well, they need to work on making good then. HOW to move it forward? I just gave some suggestions. In the end, ideas is all we can give. It's on the actual people to figure out how to use it or not use it. It is their choice, because only they know what is going on in their real life.
Polyfamguy -- hope you are doing a little better today while you process. BREATHE.