A few years ago you made a deal with the son of Hades, Sirius di Carlo, that was much like a political marriage. You wanted the power that being his wife could grant you while he wanted to avoid being forced into an unwanted marriage. The deal was that you ate the pomegranate and got trapped in Underworld with him but got control over the Underworld and Overworld in return. So when you try to break the deal, he's quite upset.