"if he was keeping it from you, there is a good chance he is at least thinking about something more happening there"

Or he knew his jealous wife would try to take control over whom he assiciated with.

If you want to get your guy (or girl) to open up, you have to make them feel safe in doing so. If he says something you don't want to hear and you jump down his throat, he'll clam and stay clammed.