It's simple: Ruth's greatest PR and legal need right now is to prove that she was ignorant of her husband's activities. Here, proof! The NYT drew a quote from Ruth's reluctant and doubtless heartbroken attorney:
Ruth Madoff, who has been married to Mr. Madoff for almost 50 years, knew nothing about the "alleged affair," said Peter Chavkin, her lawyer. While that, unfortunately, will not ease the pain of the people destroyed by the Madoff fraud, he continued, the allegation "stands as a powerful reminder, to those who say Ruth must have known of her husband's criminal scheme, that there are some things that some spouses - however close they are - do not share with each other."
In the best of all possible worlds for Ruth, Bernie would also turn out to be gay.