http://en.wikipedia.org/wiki/Puppy_love

Puppy love (also known as simple infatuation, a crush, calf love, or kitten love) is an informal term for feelings of love, romance, or infatuation, often felt by young people during their childhood and adolescence.[1] It is named for its resemblance to the adoring, worshipful affection that may be felt by a puppy. It may also be able to describe short-term love interest.