This story is a clear depiction of toxic relationships irl, believe it or not it's really common to happen especially in poor households. The Female Lead can't clearly let go because she still has lingering feelings for the Male Lead, I can't say much because I'm not in her position but it's very complex and hard to let go of a person you've loved for a very long time. Big reason why she doesn't escape is pointless, she knew the ML wouldn't simply let her go as shown that he monitors her every move.
It's also the fact that in the current time, she has literally nobody else, the public too is against her too. So i think this too played a part in that
Frfr. Everyone else wants her dead, so it's no use escaping. She also has no households skills to use in surviving a poor life (before joining the army nurse) as she was raised in a privileged life. Readers need to realize that it's not that easy to transform your lifestyle if you have no prior knowledge to survive it.
The ML abused her and destroyed her mind. She had many different ways out of the situation and did not take them. Now happy ending. No. Very sad and disappointing situation and story. No I didn't finish it. I realized how it would end around chapter 30 but I read to chapter 48 and was very disappointed with the out come. I have witnessed abuse and it is not pretty at all. Very sad and disappointing story.