Responses
You have to understand the readers know Minjae is kind but Haeil only knows that Minjae is interested in Giju. Minjae hasn't interacted with Haeil so much as he has with Giju. Plus the wording of the gossip post says the the person who posted it would often see plays with their crush which Haeil knows Minjae went to see plays with Giju. So that's why he said it's Minjae. The purple haired bitch tried to frame Minjae.
ngl haeil is kinda a bitch for thinking it is minjae and also dumb??? like why would he expose himself in the post- it's not something you do. Minjae has been always a very caring character and FL has every right to trust him. I hope minjae confronts that girl well and clears the air up it's so messy rn