A fork of Rural Dictionary
Those first weeks of your relationship where you're all giddy and over affectionate and everyone hates you.
Bob and Jane are stuck in that freaking cupcake phase! It's disgusting!
After concluding the initial timeframe of the cupcake phase (up to 5 years) you then come to a realization, you are now and forever bound to everlasting happiness. Reference Cupcake phase.
Patrick and Wendy are in an eternal cupcake phase