I have suggested to parents of infants to imagine that a child comes with a book of coupons for saying "No" 200 times (pick a number; I've said 300 before, too). That is how many times a parent can say "No," and the child really listen.
So it's good not to use them all up in the first year or two, because the child won't hear you anymore. It's good to save a few dozen for when they're teens and it's crucial.
To extend that to marriage, how many hateful statements can a relationship endure? How many fights will crack the foundation? Keep hate out of your house. Only say helpful, supportive things.
Parents who wouldn't dream of telling a child he is stupid seem not to notice saying similar things to that child's other parent. Don't be hateful, and save your fights for very important things in the distant future. (If the rest of this goes well, you might never need those.)
SandraDodd.com/betterpartner
photo by Cátia Maciel