Treat people the way you would want to be treated. Do you mind your husband or boyfriend having female friends who do not interact with you? Sometimes that kind of friendship can get too close for comfort. That is how affairs get started. Back off. Better yet, if the husband is a real man who loves his wife, he should take care of that himself. Backing off is better than getting your skull split. If you ever watch Investigation Discovery, you know what I mean. People can be crazy.
Some commenters said you should challenge her. Don't do that. It would make you look jealous and ready for a fight. If you are preparing to challenge the wife, then, you have gotten too close. Again, treat her the way you would want your husband female buddy to treat you. Most female friends lay down what they are not willing to take. Back off.