Love in dreams

People fell in love and fell out of love and broke up?Why?

Love and passion burn out after a few years into the relationship

wouldn't you remember the feeling that you have toward someone

when you first time see him in flesh and know he is the one instantly

and think how lucky you will be that you are going to get spend most

of your life with him .

Why can't that feeling grow stronger and become addiction in its original

form instead of transfering to some kind of less exciting emotions?