You brag to the people at work about the great deal you got. You tell your on-line friends about it. It may even prompt you to call your mother. To keep it running its best, you put gas in it, have its oil changed, rotate the tires, get regular tune-ups. And you do all these things willingly because you want it to last.
Relationships are the same in many ways.
When new, you delight in the excitement, the newness, the discovery. But, like a car, a marriage needs consistent upkeep to stay running at peak performance. Unfortunately, some people are more attentive to the maintenance of their cars than the maintenance of their marriage. And, far too many people decide to trade in the old model marriage for a new one when it starts running rough. Cars come with a maintenance schedule.