Great piece, Ira. I do agree to some extent. For instance, my step-mother told me many times that I should be kinder to my mother until she eventually conceded that the distance I held was for good reason.

However, when it comes to the way someone speaks to their parent, I think it's important to remember that, no matter how bad things have been between them, we always have a choice in how WE speak. I think it is a red flag, no matter what, when someone chooses foul ways to speak to a family member. Especially if, as a new partner, you haven't even been told of any difficulty between them. Personally, at the very least, I would explain to a new partner that I have a difficult relationship with my mother and that, for my own protection, I choose to maintain a distance from her, while I am still dutiful.

I do realise that your wife sought to understand, and that's probably because she had established enough trust with you to realise that there was more going on but, if that trust hasn't yet been established, or there is no hint prior that there is an actual troubled history, it will always be a red flag. I speak from experience with my ex-partner and know that there were too many red flags similar to this that I knew were warnings but didn't listen to.