I don’t know whether it is just me but this scene really pissed me off and made me question some things 

So the scene of when Do Hyun Su’s wife came to arrest him after that house help died And then he said he wouldn’t trust anyone again because how would people believe he didn’t do it if his own wife doubted him 

So I wanted to ask you guys your take on this 

It’s hard to say, because in many ways what she did showed trust - because if she believed deep down that he was the criminal after the evidence surfaced, she wouldn’t have had the courage to go home to find and arrest him on her own. What she did felt more like trying to protect him from my perspective - so he was no longer at risk from people trying to kill him (amongst other things) while he investigates. 

In this case, I would probably do the same thing as her - not because of a lack of trust but because of the desire to protect and prove his innocence. If you’re asking about trust, yes I would trust someone if it were me in that situation, but the arrest was not because of a lack of trust from the way I look at it.

It’s interesting to hear that perspective on this, as not once did I see her lose trust in him in that scene. The only point at which she was untrusting/uncertain was when the metal was at her neck, but as soon as it was gone, she didn’t run away or continue trying to arrest him, and simply wanted to understand why and convey her upset at his actions. (That’s how I watched that scene, so for me I felt heartache for the two of them rather than feeling irritation)

As long as he knows that she trust him, he doesn't want anything else, "Never change, keep loving me just like now. All I need is your trust." Hyun-so once tells her when they had a house warming party.

I think he wouldn't care about others, and he did state that once they got to the hotel, "People has always doubted me, hated me and said things about me, but I never cared, but this time, because it's you, I couldn't have been more devastated"

And she cried right away saying how can he expect her to be so trusting of him, and never doubting him. She said she isn't such a good person. and I thought she actually felt apologetic for hurting him and that's what she meant rather than implying she for a second lost trust of him or anything. and following that she cleared the misconfusion about why she did that, "I thought the police station is the safest place, and all I had thinking at that moment was taking you there."

In the end, she fully trusted him saying he didn't kill the housemaid when he insisted and repeated.

I think that the job related stress, and disappointing her co-workers could have affected her decision making in that episode.