It's giving misogyny
After Katherine comes back from being abducted, David comes to see her in hospital and apologises for lying to her and cheating on her. She says it's okay and that
"What we had, it wasn't it for you. Maybe for both of us. I can't blame you for just being the first one to see it."
This is the first scene of David admitting to his wife that he cheated on her and that is her reaction? Him being the first one to see that they weren't right for each other doesn't give him a pass to betray his partner and cheat on her multiple times. His actions were cowardly and disrespectful but it's being framed like the poor thing had to act on his feelings.
He then replies "You are kind of amazing." For what? Justifying his behaviour? Not holding him accountable? The message feels quite male centred and not bothering to focus on the effects of David's actions on his wife. To me It felt like: Yes! Wives who are lenient and forgiving to their husband's disrespectful actions are amazing and should be praised!
Also that got me thinking to when Katherine did find out about Mary Margaret and her husband. Katherine only confronted Mary Margaret and hit her. The show didn't include her being mad at her own husband. Even when David broke up with her she wasn't mad at him, it just seemed like she was frustrated and upset. The town shunned Mary Margaret after the affair, nothing was shown about any of this treatment towards David- the cheating husband. The woman in the situation was the only one to receive backlash, when David was the one committed to someone else.
Whether it was intentional or not, I thought I'd share my thoughts on the double standards in the show.