unless she knows something else and is helping to keep something a secret.
That is another piece of the jigsaw that would certainly fit the allegation, it's one thing for a wife to chose to forgive an infidelity, that's her choice (even though it may be coerced / pressured ... at some point people are adults and have to assume to have agency over their own life) but if she helped to cover up some incident with a minor then that is a different thing entirely and would certainly damage her reputation as well if it came out and would be a reason for her to help keep it quiet. Assuming the accusation is true of course.