The marriage was already open you just didn't know about it. However -- he will definitely not agree to open up the marriage and let you have some fun and adventure as well. First reason is that your husband enjoys sneaking around and lying as it provides a form of high which makes the sex better. Its like an addiction. Second -- he know very well you can have affairs much easier than he can. You could literally have your choice of guys any night of the week....so therefore an open marriage wouldn't be fair to him. Since a key point of his affair is to boost his ego, the thought of you enjoying the company of someone else doesn't work because it would hurt his ego. For this reason he will want to reconcile, go to counseling, and promise never to do it again.

Check out Chumplady.com - its all pretty easily explained.