My Friend’s Nice Mother (2017)

My Friend's Nice Mother 2017 ~ 착한 엄마 친구 - 

Twenty-year-old Soon-jae has a young mother named Ji-yoon that's like a sister to him. Right next door live a mother and son the same age as them; Ji-yoon's friend Yeong-joo and her twenty-year-old son Jae-yeong. The sons fall for each others' mothers.