Basically, this boils down to, "oh, you think you have a good marriage now? Just you wait..."
We've had bad times before. There were times when one or both of us were unhappy for whatever reason.
Being happy is nice, but it's not the ultimate point of a marriage. There's a reason the stock wedding vows make a point of emphasizing "for better, for worse, for richer, for poorer, in sickness and in health". The good times are not guaranteed.
I'm not saying this about you, but I think far too many people these days throw in the towel when they realize that the honeymoon eventually will end.