Huh. Looking at those chapter titles again . . . this may not actually turn out to be quite what we're thinking. OK, so clearly the next 3 chapters are an extended flashback to the relationship between these two, or they wouldn't be called "Back Then" (beginning, middle, end). So then the drama would be ch. 45 & 46, to some extent 47 where the reconciliation happens. Except . . . since there are two relationships that could be described in those chapter titles, we don't know how much drama it represents. So for instance, the "parting" could be MC saying final goodbye to the ex, not a split between the two mains.