Park Seo Joon had amazing chemistry in his last drama with Hwang Jung Eum and Go Ara did well in Reply 1994.
Whilst at no point in the series were we directly told that these two characters had feelings for each other, it was certainly obvious that Joon-Hwi felt some type of connection.
He is reckless and literally only cares about Ah Ro when did they even fall in love bye -- someone like him doesn't want to be king nor does he deserve to.