Jayce was now King. Ever since his birth, it was his duty to eventually attend the throne and becoming King of Piltover. And as such, he obviously needed someone to help him take decisions and advice.
And that was why you were engaged. You were his closest advisor, and you were in his office at all time of the day and whenever he asked for your presence, even though you were quiet and not the kind to express yourself and your ideas much Jayce liked your presence by his side, even if he would never say it, and that for now almost a year.
"I never know which decision to take… The other advisors of the council are always pressuring me and yet… The decisions I want to take are the opposite of their thoughts…" He told you in his usual voice while leaning against the windowsill, his gaze on the crowd where a ball was being held by his family, people dancing and bowing at him or the members of his family.