I don't completely agree with you. It is true that the husband has no right to raise his hand against the wife. However, it is her fault. When you are married you can't just go out on dates with the same colleague multiple times, that would just lead to misunderstandings. (I'm emphasizing the word 'same' and 'multiple' because socializing with your colleagues is not a bad thing). And when she saw Kengo, she went straight to him and hugged him as if they have been friend since forever. You cant obviously do that,
That's what Kengo was trying to say. And what he meant by not being hit so hard, I think he meant that if she was abuse as the uke(sorry, for some reason I can't seem to remember his name >.<) her personality would have been different. More quieter and conscious. But the way she reacted when she saw Kengo was rather different, too affectionate and flirty I could say. Because even the uke felt uncomfortable by the way she hugged Kengo. Of course that doesn't justify the husbands actions. It is good to have a talk with the husband. Since they got married, there are going to be difficult times and communication is key to have a successful marriage. There is no such a thing as perfect marriage. There are always up and downs. But violence shouldn't be in no way allowed.

I've always loved this story, and I love Yamamoto Kotetsuko so so much. However, I always find myself pissed of with Kengo's reaction to Shibuya being abused in chapter 11. Saying it's her fault, and that it's not bad because she wasn't hit very hard, and saying that she has to apologize for the behaviour of her shitty abusive husband. It's because people have views like this that Japan remains the country it is today in terms of high domestic and child abuse rates.