Hi 50wife;
Welcome to PC. As a former PO I can tell you that it is a very difficult job and the divorce rate is very high because of the contact male officers often have with women on the job. There were many days that women called my house because I gave them my card as a courtesy or if they needed to follow up with additional info. Did I always tell my wife who it was........no, why, because it was job related. Did she have suspicions... most definately, but I was honest about it all. There were times that women became a problem and I got more than my share of opportunity.
I think a honest talk with your husband is in order. Tell him that you feel he is hiding something. Ask him for the truth. If it is another woman ask him what his feelings are about you and your marriage. I am a true believer in communication. There are things he cannot and will not tell you about, but he might open up if he is asked without an accusatory tone.

As far as getting someone to trap him....that is just wrong. Also it just might backfire, LEO's are very good at picking up on a scam, especially dealing with women. A woman that comes onto him may just find herself in jail for soliciting for prostution and then she would spill the story about your little game of entrapment. How would that play out in your relationship? The best way is to be honest and tell him the feelings/vibes you are picking up. If he denies it, at least he will be armed with the knowledge that you are on his trail and that will put the brakes on it.

Best of luck to you and prayers for the safety of your husband.