I don't know of many that really looked happy, meaning to me that held hands and acted lovingly. Of course holding hands during the closing prayer was almost a given. Everyone did that to look "right" but I know of a couple who had seperate bedrooms, I know of one sister who was married and went on "dates" with wordly guys just to get some attention. She finally years later committed adultery but they didn't split up.
I think they believe that if they do all the right things that finally someday everything will be fixed and they will be happy. But I didn't see all that much evidence of it in the present tense.
A long marriage aint necessarily a happy marriage, and if the people were "in the world" they could have split and tried again . Although there was no outright ban on seperation, the social pressure was enormous and you would have been totally out of the crowd if you had done so. Many years as an elder allowed me to see things that may not have been obvious to the rest. It is easy to put on a show at the meetings.
BTW
Of course holding hands during the closing prayer was almost a given.