In both series the man is much younger than the woman and while the relationship starts as too people that make a sort of contract, they end up getting close to each other.
In both series the triangles include a 30-something woman, a man around her age and a younger man that falls in love with her. Both series show the process of changing oneself and become more likeable to those around them.
Like A Gentleman's Dignity it's a drama not focused just on the main leads. All the other characters are interesting to follow. Both dramas have funny moments.