The development feels a little rushed ngl, like seungho just realized like that? That our ...

Like you didn't realise what you got before you is precious, right?

I don't think he 'just realized like that' by himself .... there are milestones to Seungho's change of behavior:
- The 'realizing' he was feeling something he didn't know what it was: when he kissed a sleeping Nakyum, surprised himself and then intentionally tried to ignore him by going back to his harem of whores.
- The 'forceful realization' ... the whole episode with Min where he was mocked by Min for caring about Nakyum then tried to prove he didn't care by trying to share Nakyum and failing.
- The 'drunken confession and then getting sick' ... just after giving up on sharing Nakyum, when he drunk and started confessing feelings towards Nakyum
- The first conscious confession --- in the doctor's office and the sex that followed ( 'You made a wreck out of me')
- The guilt and regret realization --- the events between his punishment of Nakyum when he thought he had run away but then found out Nakyum was innocent + Mr Kim saying he was acting like his father + Seungho overhearing Nakyum telling his sister about his feelings for Seungho.
- Seungho trying to 'win over' Nakyum the proper way: everything that happened between the bathtub scene and now, including the role reversal when they are alone ( Seungho calling Nakyum his Lord, telling Nakyum to call him Seungho).

So, although it doesn't seem much, Seungho is just at the stage where he doesn't fight anymore against what he feels and more to it, he is actively trying to win Nakyum's heart ( 'Just don't push me away' he said in the bathtub == give me a chance) .

Hmm i guess so, thank you for giving me these point outs. On my point of view it felt rushed, but i guess there was some sort of development.

Omg I love this comment! It's so good to remember all these moments when analyzing seungho's behave, I had forgotten most of it hehehe thanks!

I initially figured that Seungho overheard Nakyum and Heena's conversation - i.e., Seungho is bad news and Nakyum's feelings are probably just Stockholm syndrome - so he had to change tactics for Nakyum not to leave him.

But the much-later chapters do feel like the gentleness is slightly more genuine, hahah

Oh wow never thought of it that way (⊙…⊙ )