I agree that they're both in the wrong but the main problem is that they both have abusive pasts which have cultivated exactly the habit of secrecy , which comes with feelings of shame and low self-worth. They've never had a honeymoon stage. They have been, in different ways, seeing parts of each others imperfections and darker pasts from the beginning. Remember how they got together in the first place. It's hard to disentangle from toxic family and even when you do, their presence in your life lingers. The wanting-to-show-my-best-side is kinda true both mostly just them rationalizing actions that have deeper, darker roots. Seo-an proves it because in that confrontation with Woo-won, with every good intention of wanting to help, he was his father. (Or is it the grandfather who runs the company? I forget.)
Why are we acting like Seo-an is the only one who's done wrong?
When you see your partner, not only being extorted, but physically abused by their parent, you're supposed to do nothing and just let it happen?
I love them both, but they are both in the wrong. Woowon is also wrong for keeping the stuff with his father and that other asshole from Seo-an, when both situations directly effect him, since the father was threatening to go to Seo-an and that other asshole is clearly obsessed with Seo-an and will do anything to push his buttons.
The main problem is that they both only want to show their good sides to each other, but that's not how relationships work. When you get past the honeymoon stage it's time to show your partner the not so pretty parts and if you both still want to be there that's when you know you have a relationship that goes beyond the surface.
I love them and hope they start openly communicating and can't wait for all the drama to settle down, please, soon, please.