Crazy Movie - Help!

Trying to remember the name of a foreign language movie (Asian). A husband and wife lived in an apartment, but so did the wife’s boyfriend, unbeknownst to the husband. The boyfriend would actually stand behind the husband and mimic his every move…and somehow the husband never knew he was there.

Bin-jip (2004) has something like that.

You ROCK!!! Thank you soooo much. I LOVE that movie!