What is the deal with Miranda Lambert and the crazy ex girlfriend thing?

So i have been trying to figure out why ppl act like there is some story behind the crazy ex girlfriend thing. I must have been out of it, but did she do somthing whacky? I know her and Blake Shelton were an item, but what happened? I know that she named here lastest album crazy ex girlfriend, but can someone please fill me in? i dont even know the right question to ask, i feel like an old person. After hearing Gunpowder and Lead, i love the girl shes , but i need the story people!!