*SPOILERS ALERT* One of the best ways to know that one main lead is falling for the other in a K-drama is when the former shows off their jealous side.
In It's Okay to Not Be Okay Ep 8, we saw Moon Gang-tae (Kim Soo-hyun) getting frustrated beyond belief when a fan (cameo by Choi Daniel) gets handsy with Ko Mun-yeong (Seo Ye-ji) under the pretense of having a fanboy moment with her.
The website celebsbar.com is an aggregator of news from open sources. The source is indicated at the beginning and at the end of the announcement. You can send a complaint on the news if you find it unreliable.