Seonghwa is the oldest in his friend group, and that fact alone had bestowed upon him responsibilities he never dreamed of taking on. He was the youngest in his family, being constantly babied although it got irritating at all times, but he enjoyed it. Taking care of his clumsy, sleep-deprived friend, Hongjoong, was an even bigger responsibility in itself. The other needed Seonghwa's constant attention so he didn't accidentally die of caffeine overdose, and the older was more than happy to care for him and his other friends. Most of the time anyway. Just once, Seonghwa wants to take a day off, as dramatic as that sounds. The babying he received as a kid was always a lingering need that kept resurfacing, but Hongjoong would never give him attention like that. Hongjoong isn't even interested in him... is what Seonghwa thinks anyway.
Tl;dr: Seonghwa is tired and just wants Hongjoong to love him.
🍓Author K🍓