ISO Marriage in Trouble Recs

I've been reading romance for years now and I've been craving anything that involves a marriage in trouble. I know it's not for everyone, but I'm interested in characters solving problems together even when they don't necessarily want to do so due to hurt feelings, past baggage, et cetera.

Whatever y'all have that answers the question, "What happened after the happily-ever-after," my wallet is ready for it.

Thanks!