Guillaume wrote:it was all about questioning the status of Homer and Marge's relationship
That's the thing, it didn't really go down that road. Usually when they do a marriage crisis episode, Homer will do something boorish, Marge will get angry and question why she bothered to marry him, Homer will make some grand gesture (perhaps with an over-the-top, too silly to be funny or exciting action sequence) and it will all be resolved in the last couple of minutes. Here, we were presented with a realistic situation of Homer not being around as much due to his new duties at work and Marge feeling lonely and tempted by Flanders, whom she's been shown to have a high opinion of in the past and was there while Homer was not. It really didn't feel like a run-of-the-mill marriage crisis episode to me because there wasn't the usual crisis and it all happened rather organically.
I'll still defend the ending as gutsy with the current trend of mean-spirited humour, especially compared to the assorted Seth MacFarlane shows. It's not that much sappier than the ending of And Maggie Makes Three or other episodes in the classic era, though I know not everyone is a fan of those endings now or back then either. As I said, I think with the amount of laughs the episode had (especially with the dice earlier on) and given the story, thirty seconds of mush at the end is acceptable.