Did he really think his roomates were messing with him at the time? Why would he think that? Thats an odd mindset. Since they were actually teling the truth
Teenage boys can definitely be little assholes to each other, for absolutely no other reason than because they can. Its understandable why he might think his roommates are pulling a prank or joke.
My friends(all of us are guys) always loves to joke around, That's why if they said something odd i usually think it's just a prank/joke, Maybe that's why Haesoo didn't believe what his roommates said before ( ̄へ ̄)
Judging by the fact her face is also hidden, she wasnt a very good parent either to them even if she did try to get them out of the situation
She put them right back into the situation. She didn't take them out of anything.