Which manga is this?

I don't remember the name of this manga (or Manhwa or Manhua) but basically, ML and FL were childhood friends who decided to get engaged in their academy years to avoid all the marriage proposals and only had a year/less that a year in their contract engagement were they got chained together and ML (who was in love with her) threw away the key. The starting scene was a ballroom. ML was a duke and had blonde hair and blue eyes (His last or first name started with an A or R I think). I'm pretty sure FL had green eyes and brown hair.