I don’t think it matters if he is narcissist or not. And they can’t really know on online forum. He does sound like one possibly by what you described, but does it matter? I think the only thing matters is if you feel content in your marriage. If you are, then who who cares about online forums and diagnosed.

But if you aren’t, then it doesn’t matter if he is narcissist or simply a jerk or you are just a bad match. I also think women on that forum likely just want to help the best way they can in online forum.

They might also be hyper vigilant when it comes to abuse/bad relationships. They might see things differently as they’ve been there.

Take what’s useful for you and disregard the rest.