The only thing your friend needs to be concerned with Wulf is this:
She made her husband a promise, and now is relenting on that promise of her own free will for purely selfish reasons.
It doesn't matter if she had good intentions, it doesn't matter if she cheated on him, it doesn't matter if she is the best person in the world. She makes promises like "forever and ever, til death do us part" but means none of it. She throws promises around with little or no forethought and breaks them just as easily. Can you ever trust a woman like that, again?
Tell your friend that if these are her true colors then he should be thanking her for showing them at last. He sounds like a good guy, he'll bounce back, and she will still be a lying selfish spoiled little Indian-giver.
That's how I see it anyway...