Together time doesn't exceed 15% of week.
Keep it fresh, like milk and rhymes.

Have a cheat clause.
Every 5-10 years, have a "don't ask, don't tell" free fuck with a stranger. Each of you.

Both people must have their own shit going on.
No riding of the coattails.

Two televisions in the house, two bathrooms.
obvious.

Jealousy is off limit.
Keep psychotic, irrational meltdowns out of it.

Drink alcohol.
Solves problems temporarily. The couple that drinks together loses enough short term memory brain capacity to assist in "not sweating the small stuff".

Embrace anger sex.
Better than domestic abuse, just as soul cleansing.