as for sumin and sungji, what do you mean better way to develop?
Another way is a better way I'd say. This main couple's love story is nothing other than porns now. Their sex moments happened all over the place. There were supposed to be serious communications between them; Sungji was supposed to call for an explanation to rebuild the trust if what she really needed was an assurance, and she should have asked about Sumin's pasts if what she really wanted was to have a long-term relationship with Sumin, yet she preferred to see how Sumin would look during sex more. What a lovely-dovey relationship they're having there! Why was she not afraid of getting cheated on again? Really, did the author have to make their make-up story this ridiculous? Like they were lucky because suddenly, Sungji was horny, and in a rush to learn how to be a top, otherwise, they couldn't have made up yet, could they? How unpredictable! Being blinded by love doesn't necessarily mean that you can no longer control your sexual desire. Again, is it even realistic for a person to feel like having sex with their cheating partner that easily?
It took Sumin 10 years just to realize that a toxic relationship is toxic. And Sungji is the one for Sumin because she just happens to be the girl Sumin is seeing at the moment. Also, it doesn't take much effort for Sumin to completely forget about Seju whom she, at the end of the second arc, said that she had to cut tie with because she was still in love with her to the point where she was afraid that she couldn't love Sungji earnestly and she might end up coming back to her once again. It was clearly shown that Sumin couldn't even trust herself, or think of Sungji as someone more special than her exes, why suddenly now, she can move on with Sungji. Since when was Sumin this confident to live without Seju? How can this be a good writing? I'm sorry if I sound sarcastic. I'm just so disappointed with the whole third arc.
The only thing consistent about this manhwa is the art.
Neither the art; Sumin's size suddenly changed. lol