Complex sentence: This is mainly because Seok-hyun keeps her at arm's length and does not want to get married however, even after they break up Yeol-mae and Seok-hyun remain friends and are present in each other's lives.
Split into simpler sentences: This is mainly because Seok-hyun keeps her at arm's length and does not want to get married. However, even after they break up, Yeol-mae and Seok-hyun remain friends and are present in each other's lives.