You heard the person you love said he didn't love you for the past 6-7 years of your relationship and still think you could work it out by communicating? Nah, even without Hyundo, Yumin should just focus on herself.
Have you forgotten that she did this fake dating so she could get a reaction from him? She was still hoping. Luckily she got Hyundo to wake her up from being delusional.
If Hyundo is not there, she will not have thought about the fake dating as well because looks like she doesn't have much male friends or males around her. And if say they worked things out, because she really likes her still, you'll always have doubts now if you gave him another chance, because it's either he truly change or love you now, or he's being more careful not to get caught again.
That's the point. At the beginning, she was waiting for him to reach out to her. Sadly, Iseon timing is too late because she already moved on. But imagine if Iseon reached out to her while Hyundo dgaf about her because he was busy waiting for his ex too. Yumin and Hyundo do not have a good start, if Iseon moves first, we will never see the development of HY and Yumin
But if this is a second chance romance, probably dropped it at chap 1. Good thing it's not.
If Hyundo is out of the picture, Yumin and Iseon could work it out and get back together. All they need is communication. This is why the author first end things with Hyundo and Sejeong to help Yumin. What she has been looking for Iseon for six years, she got it from Hyundo in just a month. I hope Iseon will keep his promise to support Yumin in everything that will make her happy.