This is such a fantastic story! I find it so captivating, much more so than many (most!) published books I have read!
Are you going to incorporate an affair? If so, while one starts to get tangled in the web of an affair, the other should have a change of heart and go to the other, only to find their spouse cheating... just an idea, or is it just too scandalous!? Anyhoo, whatever you decide to write, it's such a good story! (Just a little tip, remember to check your grammar, like your there, their and they're Etc. It's probs just a mistake due to wanting to get all what's in your head onto the screen haha, just a little tip to check)
Loving the story though! Wish I could write like this :)