During we got married Naeun and Taemin, episode 17, The apink members said that Naeun was interested in kai to provoke jealousy, but who knows? It might me true ;)
*If you want to watch it, its episode 17 even though I mentioned it already, and its near the end of the episode. And it's the part where there all sitting down. The scene also happens after the members send Naeun out to buy coke. Search up the video and watch it for yourself*