The parents in one of my saves suddenly had red in their friendship bar. I'm at a loss as to how that came to be. He's not stepping out on her — at least not that I have witnessed. This was bad news. The storyline requires that they have a fifth child. In trying to understand what went wrong between them, I checked out their moodlets. Seems their last woohoo, she wasn't satisfied. This put her in an angry mood. I have to laugh, because while she was unhappy over it, his moodlet showed their woohoo to be very satisfying. I'm not sure just how I got them over it. I did have them interact more and by some mythical thing they did get flirty. This paved the way to satisfying woohoo for her and a pregnancy. Now, my storyline is back on track. But it was not without some tense moments on my part.
Best of luck resolving their issues. I do hope you'll post wedding photos when the issue is resolved. :)