She may want to protect her husbands job and income.

She may be having her own affair.
When H and I met with OW's H for the purpose of exposing the affair, and so that my H could apologize man to man, we found out that OW's H already knew about it.

NOT the response I expected.
We both think he was using her adultery(s) to justify his own.

But, ain't my business.