M looking for this one

Key plot points I remember: the male lead is a blonde crown prince who had previously married a princess, but he secretly divorced her after discovering she’d had an affair with a poet (he never tells the family why). He then steps down as crown prince so his twin (named Lucius) can become king. Later, out of necessity, he marries a poor girl who’s the granddaughter of an old noble family — he’s a heavy drinker at first, wins “eligible bachelor” style trophies/events, and only gradually starts falling for her. His family is puzzled about why he divorced the princess. It’s an older series (not a modern webtoon) with a European-feudal/fantasy vibe. Does this ring a bell for anyone?