@Irrriiiiii Because Ho-in has known Woojin longer. That is his best friend. I think he thought process is, again, that Woojin knows what he went through to wind up with Chunwoo why would he go and sleep with Chunwoo. This isn't like Chunwoo was caught with a random man, this is Ho-in's best friend of years. As the comment from BL G** BELIEVER says Chunwoo needs to step in instead of just freezing and watching. If I found my best friend and significant other in a compromising position with each other, I am going after my friend first. I can deal with my significant other later, especially if we live together.