You broke up, you moved on, but you're curious now: how do you classify your relationship with your ex? Why not classify him/her as a candy? It's easy to understand and can be fitting for those bittersweet memories.
"Try both and pick a side." This person has a Dr. Jekyll and Mr. Hyde personality: sometimes sweet and gooey, and sometimes crunchy and a bit rough. Hard to miss that dual nature!
Sour Patch Kid
"First they're sour, then they're sweet." At first, you can't stand this person and you want nothing to do with them. Once you recover from the split, however, you realize it wasn't all bad and that you can actually stand to rekindle the friendship.
"Make the most of your break time" or "have a break—have a Kit Kat." A Kit Kat perfectly describes that on again, off again relationship you had. Is it time to give your relationship a break for good?
Sweet Tart Chew
The one you spend forever trying to unwrap, only to realize you didn't want that mess anyway. This person lingers around anyway, too sticky for you to brush off.
"Snap, Crackle, Pop!" You had instant chemistry with this ex, but things went rough quickly and then blew up. You probably only dated a few months.
"You're not you when you're hungry." This ex made you someone completely different; your friends told you they didn't like hanging out with the two of you. You were really only with this person out of fear of being alone.
Your time with this ex lasted a long time, but ultimately it wore you out. You still have a sweet taste from them and look back on the relationship as a happy time while it lasted.
So now you have a convenient explanation for your ex. You can sum him/her up in a couple of words, thanks to candy slogans. You can now box it up and move on.