Namjoon got discharged.

Why was he admitted in the first place you wonder?

He was abused. By his own mother.
His sister being the lovely sister she is, took him to the hospital and got him admitted.

Namjoon has been pressurised by his parents a lot. Especially his mother.

If he didn't reach the goal his mother set, his mother punished him severely.
But this time, the punishment went overboard and Namjoon ended up being extremely pained.

When Namjoon felt like he couldn't do this anymore, he felt the need to end himself.
But Seokjin held him in place and he admired him because he too suffers.

Seokjin was special and despite being that, he always showed positiveness which Namjoon wanted to do as well.

Seokjin being mute didn't stop him from making friends and having fun.
And Namjoon wanted to do it too.