I have a Theory

Well I have two about love and marraige.

First I think the deep love we all want cannot be felt until you have actually gotten married and made the covenant in the Temple. As in, you wont feel that before hand thus there is a bit of faith involved when you do decide to get married.

The other is if you wait toooo long there is too much room for dissapointment. Meaning, if you date someone for several years its likely you will find many reason not to get married and rather than make a commitment you can get out. When you get married its a way of saying you take the other person and all their baggage and you promise not to leave them hangin.