It's said they've been dating since the end of last year for 4 months now.
"As Tiffany and Nichkhun are both representative K-Pop stars, they have been meeting cautiously. It's true they've been close for a long time to the point that they were rumored to be dating since a while ago. It seems like since they have both lived in the U.S., they had a lot of similarities and remained close. However, they've only recently progressed into a couple for the past 4 months."