Didn't we see that Ben was waiting for her on The Other Side in the One More Day dreamsequence thing, too? Peter basically FORCIBLY DENIED her the comfort and lovin' of her husband of decades, and even the memory that she COULD have had that, and now he's mad that she's trying to find a little sugar elsewhere? Geez Pete, what do you WANT from this woman? You are not the only man who she gets to care about!