Even so, the snu-snu at the beginning kinda gives mixed signals since the ML is pretty much deceiving her and intentionally inducing her heat. But ch18 was hot as hell so I mean..

1. Prelude to the wedding and introducing the twin switching concept
2. MC and ML (under disguise as Jihoon) flies out to Singapore and then snu-snu (MC will find out his identity on the trip)
3. MC feels betrayed and wants to go to a hospital for contraception. A junior from school kidnaps her at her appointment, takes her elsewhere to blackmail, and ML saves her by putting down his pride and dignity (plot event to give ML some love points lol)
4. Flies back to Korea, news breaks everywhere about the affair and engagement. MC will break the imprint ML put on her but ML will keep her imprint since he loves her too much (and now that they aren't really together anymore due to the deception and other misunderstandings, so it's all he has of her). This is, to put it simply, to torture himself and may possibly end in his death.
5. MC finds out about ML nearly dying since he's rushed to the hospital. Now she starts thinking about her feelings and eventually confesses that she likes him before he goes through surgery to remove her imprint on him (since it'll basically kill him if he keeps it).

ch70 is basically the confession so I guess I dropped it right after she confessed..