The state that occurs when you know that you really do want to spend the rest of your life with the person you said "I do" with.
When you can row and afterwards, all that happens is that you:
a. Understand each other better
b. Have a lot of fun making up
When you can imagine what life would be like to be without them, and the thought terrifies you
When you would rather listen to them snore than sleep alone.
When you would rather be silent with them, than talking to somebody else
When you still desire them, despite the fact they have put on 20 pounds, or started to go bald
And
When you think about we before you think about I
Then you are happily married