"Why did you not defend me?" may not be the best way of expressing it but I don't see it as a demand or accusation. I see it as a hurt wobbly person asking a wondering wobbly question.
Since you are reading NVC materials -- perhaps could ask her to share in that reading? Because right now the answer is "Because I did not know that was your expectation/want/need."
If she wants to reframe the question in NVC style,
maybe it could go something like...
"I read the responses to your thread online. I did not see a response back from you in your thread that defends me.
I feel hurt that you do not defend me online because I need to feel safe with my spouse when I am prickly and vulnerable and not so exposed.
Could you be willing to write a response online / stop adding to the thread/talk to me about the TMI line for online things/ ( <---- or something else she wants you to do that would demonstrate "defending me" behaviors to her... I am guessing here)
So I can feel that even though you are going through your own grief process right now and need support from other people, you understand that I am going through one too and need support from you in the way I wish to receive it?"
Or something like that where she lays out what her need it up front?
Then you can say "Yes, I am willing to do it like that" or "No, I am not willing to do it like that."
Move it forward
rather than keeping it stuck in the hamster wheel. Nobody can mind reader anyone else.
If communicating leads to the same place as silence, what is left?
When staying silent and being communicative leads to the same space? I'd suggest going communicative. State willing to try. Then YOU at least are being present and accountable at the negotiation table. Not showing up at all
Showing up = being willing, intent of trying to connect.
Not showing up = not connecting at all, maybe distancing.
The other people have to attend the meeting and be present to for it to fly of course. But could not let it bomb because YOU were missing and not present. This matters to you? SHOW UP to the table. Keep going -- esp with the NVC skills learning.
If both are at the table? That's good. Then maybe the next baby step could be investigating your conflict resolution method? Perhaps experimenting with different ones
until you get a method that serves you both better?
HOW you communicate things is as important and WHEN and WHAT you communicate.
I think it's hopeful that while struggling, both are still willing to keep trying and are still showing up to the table.
Could tell your wife that you are sorry she is hurting and feeling undefended. You were not aware at the time because of the shadow of your own grief/struggle. Could say if you are willing to talk about that now that you ARE aware to see what specific behaviors in the realm of online disclosure she's comfortable/not comfortable with. It's the online TMI line thing that you could sort out between you so you could get what you need (outside POV, support, etc) AND she gets what she needs (free of her feeling overexposed.)
Again... moving it forward.
Hang in there, both of you!