Translation of "Girlfriend" in Korean

My girlfriend and I decided that we could

저와 제 여자친구는

Not my sister, not my girlfriend, and certainly not my niece.

희망하죠. 여동생도, 여자친구도, 당연히 조카까지두요.

But the moment he starts to interact with his girlfriend, Kay,

하지만 여자친구인 케이와 교감하는 순간