Canadian overstayed in the US without passport stamp

OK.. I should have asked if there is no point in filing for the GC now that she has overstayed??..

But now I see what you're saying. I know these type of situations are forgiven but given the current state of this country and the bad shape it's in, I would think CBP would be a little rough around the edges in a situation such as this one. Or... maybe it will not affect it at all

CBP might correctly take a fit and not let her back in.

However, CIS, which would be handling everything to do with the GC petition, would have to follow the law, which is that if entry was legal, GC wil be awarded, with possible payment of fine.

That is why it is absolutely crucial that she remain in US.

if it is proven by the applicant that the marriage was spontaneous and not planned before she/he entered the US, then green card will (usually) be granted, regardless of overstay. BUT it is not advisable for the applicant to leave the country before the green card is given, otherwise they will be ineligible for re-entry based on immigrant intent.