For a romance manhwa to be good, it needs a compelling storyline. This could involve obstacles the couple has to overcome or a unique setting. Also, the art style plays a big role in creating the romantic atmosphere.
Sure. 'A Good Day to be a Dog' is a great manhwa romance novel. It has an interesting plot where the female lead turns into a dog under certain circumstances and her relationship with the male lead is both funny and heart - warming. Another one is 'What's Wrong with Secretary Kim' which is also popular. The story of the boss and his secretary falling in love is very engaging.
One popular romance manhwa novel is 'Solo Leveling'. Although it has elements of action and adventure, the underlying romance between the main character and some of the supporting characters adds depth to the story. Another excellent choice is 'Orange Marmalade', which deals with the relationship between a vampire and a human in a school setting, exploring themes of love, acceptance, and prejudice.
Single romance manhwa often focus on the emotional journey of one character in finding love. They usually have beautiful art and heartwarming storylines.