"boyfriend" is "남친"(nam-chin) in Korean.

Namuchin (남친) is an abbreviation of "Namjachingu (boyfriend)". Although the literal translation is the "male friends", most that it points to the specific male actually are dating. It means "boyfriend".
Korean couple a fairly conservative, more men older, conscious that it is strong. Although as especially marriage tend to dislike that the age of the woman is much larger than the male in both men and women, in recent years has been such a thought also have gradually faded. By the way, younger boyfriend called "연하의 남자 친구 (Younger Boyfriend)" younger is " 연하 that (Jonah) ". On the other hand Older is "Yeonsang (Older Boyfriend) ",