one can not understand love if they don't experience nor cherish it. If love is only attraction, then why do you love your parents? What's so attractive about your folks that keep you wanting to care for and appreciate them?
And the puppy love thingy, its nothing more than just being young. At the age and level of maturity, we just aren't able to handle our emotions, attraction and urges.
Think of your favorite food from the favorite store. Somehow, its different when its prepared by a different person using different receipe. It is that unique taste that you are in love with. You can make minor changes by asking for more or less oil, salt, chilli. But, if its cooked completely differently. It will never be the same taste that you love. Staying happily in love is about finding the right taste for the couple and they will enjoy great fruitful taste together.