Looking for a Korean song by a female

[meems]

I'm looking for a Korean song. I don't know the name of the singer or what the song's name is. But what I do know is that it's a female singer & it's a sad love song. I have watched the MV and I still remember it.  

In the MV, the girl (singer) was dressed in white and she looks very innocent. I also believe that she's dead because she was following her live boyfriend around who she later finds him with another girl, (her friend I believe) in bed. On the bed scene the other girl was dressed kind of sexy (in Korean standard). While they were making out, the guy just stops and breaks down crying. The girl (singer) who was watching was of course crying her eyes out. In the end of the MV the guy left girl 2's house crying and the girl (singer) disappears.  

I think this is a female singer that belonged in a group but went solo and this is her 1st song. It is a sad song.

If anyone know what song I'm talking about please help. Or you think it's this song please help. Thank you.

sorry if I am posting this in the wrong section.