Two guesses, potentially both needs to happen:
1. Dohu will commit some sort of self-sacrificing act or other display of loyalty/love. This is important bc Juheon does have some valid trust issues. Not just stemming from his family, but also the fact that Dohu himself has covered up his intentions and knowingly expressed misleading statements of affection. Essentially, he'll need to win over Juheon's trust.
2. Whatever evidence/blackmail that the aunt has against them needs to be cleared away. Recall that the aunt threatens Juheon around the time they break up, and it looks like its something that Juheon is still working on.
Love that idea.
I don't think Dohu has ever knowingly misled Juheon, which is why he was surprised when Juheon declared they were in a relationship. Dohu is slow. He might be able to pick up certain things fast, but is very dense to certain human's emotions, in particularly love. It was Juheon who misunderstood Dohu's intention. Though to be fair, I believe Dohu has already liked Juheon very early on, except that he was too dense to recognize his own feelings. He already had blushy ears and racing heartbeats in early chapters. That's why he unknowningly showered Juheon with affection. Even the very first time they did it, Dohu wasn't fully on board up until he saw Juheon's disappointed face. Dohu always has soft spot for Juheon.
What is your theory of them getting back together ????