To most people, it begins with a grand confetti-filled ceremony, but sadly, usually ends in divorce and the like.
So, taking contemporary relevance into consideration, Perhaps the most accurate definition of 'marriage' is:
"I know im crazy in love with you right now, but when these high emotions leave and it's just you and me left, I promise that I'm going to stay with you, belong to you, protect you and love you... I wont leave you or break this promise (even if you do bore me sometimes down the track)."
"If we're going to consider marriage, we'll have be prepared to make the commitment... forever."