Is she a tenant with a signed lease? If not, then no the money she's providing him is not considered income.

Just like if you had a boyfriend that was giving you money, that wouldn't be considered income. The only exception to that is when an ex-spouse is receiving alimony and then lives with a new person...that can lessen the money they receive from the other person.

But if you're not paying him any alimony...that wouldn't apply. Basically, her income has nothing to do with you and your ex's agreement.