If you aren't going to tell us what she did, how can we advise you whether or not you should forgive her?

The only thing I can say is that if you deemed whatever it was serious enough to say you could never forgive her, then I'd be careful about having a relationship with her. It would be grossly unfair to subject her to your resentment about it for the rest of her life if she is genuinely remoreseful.

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