well, i feel that there is nothing wrong at looking at women. However what went through the man's mind after looking at the lady is. Some ladies may feel that their husbands have strayed mentally if they have fantasies about other ladies. This is difficult to prove... For your hubby, smiling after looking at other couple getting initimate, may thought of the times whereby you guys had gone through during courtship. As for the email, I will encourage you to believe him, till otherwise proven. Trust is very important in a marriage. If there isn't trust in a marriage, I doubt it will last long.