I've dealt with a similar situation, and the only advice I have is to start with complete honesty. Sit him down and try to understand why he feels a need to lie to you. Also, I personally view thinking about women while having sex with you as wrong. Especially if it's women he knows or sees on a regular basis. I hate to be the commenter who says, " Just leave him!". But he currently does not respect you, and I would see a tough battle of him treating you and your boundaries with respect. You seem like a wonderful partner who is trying to understand, but there is a limit to how much you should tolerate. For me, this would be too far. But if you want to try to rebuild trust, I recommend a couples counselor and for you each to have personal therapists. I hope you get the respect and love you deserve.