It represents sweetness and warmth. Popcorn tastes sweet, some are shaped like snowflakes, but it tastes warm. I guess what that boy means is: Although it is very cold on Christmas Eve, I feel very sweet and warm with my girlfriend.
There is a song "Love is like popcorn", as the lyrics say: Love is like popcorn, it explodes and bursts. Love doesn't explode, so you can't tell true from false. Love is like popcorn. We both like it. It represents love. Love is like popcorn, warm and sweet.
The implication of popcorn
Popcorn has a moral: popcorn, from one state to another, from a state that you usually think you can't eat to a state that you think you can eat.
It is a potential food, but when it breaks out, it will immediately become something you can eat and something that supports and nourishes you.
Popcorn is a symbol of your transformation, and it is the state that you will transform and release. If this seed persists, or resolutely maintains its hard-core character, it will never burst and become your favorite light and fluffy popcorn.