I know you already have an answer in mind and one selected, but I felt that this also fit.
A person and some candy
Complete me. Dive into me. Stay until you're soft. Just crumble to pieces
It can complete someone's cravings. You "dive" into food you enjoy. Some candies are soft or crumbly.
We're the gift for the giver
Candies can be used as gifts, like on Valentine's day.
The monster's delight
Snickers, "you're not you when you're hungry."
I see past your eyes and into your soul
Chocolate is often a deep craving for people but they try to suppress the unhealthy urges.
But our love, as sweet as it is, will never survive
Candy can be sweet, but you eating it means it won't last long.
You're Romeo; I'm Juliet, doomed from the moment we met. We'll never keep her promise.
The candy is doomed to be eaten from the moment you get it.