Nobody should be smug because nobody is perfect and nobody's life is perfect.
I was married 8 years, was single 14 and only recently met new partner. There are pros and cons to both situations. I've friends who just this last month have celebrated 10, 20 and 25 years married. They'd all say it doesn't happen by luck it takes work, communication and love as a verb not being complacent about it.
Marriage was a mistake, knew it on my wedding day but wouldn't admit it to myself let alone anyone else.
We argued a lot and quite loudly. We had these SM neighbours who were best friends with another couple in the same block of flats (also SM) but only the woman from the first couple tried to offer saccharine advice and make out they were better than us. Even veiled refs to me not keeping husband 'sexually satisfied' 
We moved out but I still stayed in touch with a friend who also lived in the same block of flats.
Can you guess where this is going?
Turns out the husband from SM Couple 1 had been having an affair with the wife from SM couple 2. It all kicked off one eve when SM husband 2 found evidence and basically went for the guy shagging his Mrs!
Now nobody deserves to be cheated on but sometimes there's proof that karma exists.