@VirtuousVillein well, if you read again at that moment he told her his feelings to her, and how he talk about "how I talk to male lead about my feeling to you", its not like he just admit that he had unrequited feelings. Its literally he want and demand answer from her. Because as far as I know, many things like this happens in real life if that case you said happen. Just say, I just confess to a girl I like, and now we are dating. Now when I talk to my friend, my friend will say "maaan, I use to like your girlfriend. But you got her. Gratz man". And I guaranteed, mostly they will just laugh at it.
But from this situation and flashback when He told male lead, and how he confessed to the female lead, its 100% guaranteed he isn't like that. Thats why suddenly Male lead making space to them, he feels bad or whatever reason.