It's impossible to say every good marriage is successful thanks to just one thing.  So we'll boil it down to SIX things.  That's WAY more reasonable.

A new study of more than 10,000 couples in 110 different countries found the SIX secrets that were true across almost EVERY happy and successful marriage . . .

1.  Mutual respect.

2.  Deciding divorce is NOT an option.  Successful couples decide at the beginning that there's no plan B . . . this is IT . . . and that leads to more patience.

3.  Daily rituals.  Whether it's having coffee together every morning or watching the news at night, having something you do together every day is key.

4.  Spirituality.  Virtually all the couples believed in a higher power.

5.  Not worrying about sex.  The study found that if you take care of the relationship and communicate, the sex will take care of itself.

6.  Putting your marriage before your kids.  If you make your marriage the priority . . . and don't just focus 100% on your kids . . . it keeps your marriage strong.  Which is important for your kids AND you . . . since THEY'RE going to move out one day, and you'll still be there together. 

(ABC News)