What is the origin of the idiom "puppy love" and when to use it?

The phrase is thought to have originated in the 19th century, when it was used to describe the love between a young boy and his dog. The phrase is now used in a more general sense to describe any young person's first romantic relationship. It is typically used to describe the early stages of romantic interest or attraction, especially among young people. It emphasizes the youthful and naive nature of the relationship, highlighting the lack of maturity or depth.