I never noticed this before, but apparently its a well known "happy new year" present in Korean entertainment.
I'm going to assume that Dispatch gives the managers of the celebs they expose a warning, and I'm sure theres plenty of shady stuff going on like blackmailing couples into giving them any other gossip in order to save them from getting exposed but we'll never really know. All we do know, it its been going on for at least 4 years straight...
2013 - Rain and Kim Tae Hee
2014 - SNSD Yoonha and Lee Seunggi
2015 - Lee Jung Jae and Lim Se Ryeong
2016 - Junsu and Hani
2017 - Due to the ongoing scandal and impeachment of the president, Dispatch cancelled their announcement, but rumors were that they were going to expose Song Joongki and Song Hyekyo...
For 2018 it will be interesting if they respect the somber time in the enertainment industry right now or if they will expose a couple this coming Monday :/