Maybe your W doesn't mention Om anymore because their R isn't as great as it once was. Maybe things are on their way out. Like the book says, most A's don't last longer than 6 months. Turn the situation around. Instead of assuming they are together, pray that they are fighting, and having a crappy time together.
Feeling guilty about the EA isn't always bad, but it may take awhile for her to get over those feelings. My H decided to go to MC with me after straight out telling me time after time, that if you can't fix your own problems at home, then you have bigger problems than you realize, and the MC won't help any ways. So I made an apppoinment for me to go alone, and when he found out, he asked to come. He said that he was having a hard time with guilt, knowing that he hurt me and our D. But on the other hand, becuase of the guilt, he didn't want to come back. That he wanted to be in love with me, and not be together just because it would make me happy, and everyone expected himtoo. He has to be happy.
Sometimes all you can do is wait. Watch for baby steps.
I saved my marriage and so can you....Its all about positive thinking...