[matthewb0051]

I've conducted dozens maybe hundreds of investigations into similar conduct. With near 100% certainty the guy was fishing for a hook-up (as the kids say).

Unless he was including you in the messages, he was fishing.

I agree that you don't tell her what to do with regard to him. My theory is that it is her life and if she choses to venture outside of the marriage vows that is her call. I would not like it but its her call. You start down the road of telling her what to do and you might not like the outcome.