Marriage guidance

In Competition No. 3020 you were invited to submit the formula for a successful marriage courtesy of a well-known husband or wife in literature.
 
Some time ago, I challenged you to do the same on behalf of well-known poets, and if you like your advice brief and to the point, there’s always Ogden Nash’s ‘A Word to Husbands’:
 

To keep your marriage brimming
With love in the loving cup,
Whenever you’re wrong, admit it;
Whenever you’re right, shut up.

 
Your prescriptions were less pithy, but no less impressive for that.