I'm pretty sure its garam's heart on the last panel, since it had many cuts and also it ended with "and so, once again...". I'm pretty sure Garam's wounds are the ones that are reopening(With the string barely hanging on). It wouldn't be long before they reopen if Heejae doesn't act fast.
Maybe I misunderstood, but I saw the stitches on his heart being sewn up, and yes, haejae, he should pull yourself together because I honestly don't think Garam can handle this kind of behavior again... especially seeing the old wounds in his heart was so sad.
Of course Garam giving him silent treatment wasn't enough. But i trust Heejae will apologize after this (If Garam being straightforward is still not enough, i don't what will). The author also posted Compton as wip, so i think it will be his next step to become human.
Ah, the cliffhanger is killing me:)
I think we'll see Haejae apologize. Even though Garam accepts Haejae like this (Haejae buys him some flowers, which he says he found difficult because it's not the season. He says he always wanted to give them to him because they represent Monet. Garam smells the flowers and asks if it would have been harder to apologize instead? Ofc everyone is shocked. Then he says something like, 'If it's hard, you can say so, I accept professor like this.' Finally, we see stitches being applied to the open wound on his heart. As I said, I think the moments when we will see Haejae's apology are near.