I felt the need to respond to this post. I agree that the feelings about OP should not be discounted as fake or unreal. They are real and are usually the result of something missing in the marriage. However when we refer to our spouses being in la la land it is because there is more to a relationship than the initial attraction and feel good emotions that the affair has. In my case, all my H and OW do is go out for dinner, and drinks and fool around. Their relationship does not have to deal with the stress of everyday life such as bills, dealing with kids, the everyday chores at home etc... The new relationship is exciting but it is ALL FUN. If all my H and I did was drink and party we would be the happiest couple in the world. But that is not REAL life. As for the physical part, my H and I have a great sex life and still do. His is more of an emotional affair and we have both identified what was lacking in our R, unfortunately he has turned to someone else to get it. I do not discount his emotional attachment to OW, but I know that it will probably not be as attractive to him once the stress of REAL life enters into it.
I do agree that marriages need to be more like 'affairs' and people tend to become complacent and don't put forth the effort needed to keep each other happy as they were in the beginning.
