My W has a similar issue. Usually when her stress level is at it's highest or when something in life happens that includes even a small betrayal.
Did anyhing recent happen to put this at the forefront in your mind?
My wife knows we are past the point I would bring her A up and get angry with her, but she did develop a being hard on herself phase during R. She did it because if she thought those things about herself then anything I could bring up did not sting as much. She thought if she pinished herself then I would not see the need to do so. To be fair I did punish her at times. Not proud of it, but it is not like I wanted her to suffer worse. I just wanted her to be suffering the same as I was at that time.
I think one thing that gets tied up with a BS'a forgiveness is that a lot of WS assume means it will naturally lead to them forgiving themselves. It rarely does.
I told my wife once that I can offer forgiveness to the wrongs committed against me (I did that for me BTW), but I can't forgive wrongs committed to others. I also can't offer absolution to her. I am not at that level
FWIW I would share this with your W. You might be amazed at her perspective and advice.