Muffins in the US can be sweet, but they'd taste weird with frosting on them. Idk what you'd call unfrosted cupcakes. Miniature cakes? What do you think, @bethorien?
cupcakes are always cake. They are literally just small cakes. A muffin is a bread. a muffin can be sweet but so can other bread like zucchini bread or banana bread. It's made a completely different way and with different ingredients and is often savory rather than sweet.
I mean, you're still dating her right? So not your ex i wouldn't consider it