This is not relevant. An annullment might point to the fact that one or both spouses did not have the needed information at the time of their wedding but has nothing to do with the amount of knowledge they have regarding actions during the course of the marriage.
Please give me an example of how someone could commit adultery without full consent?
Of course not. That is why I have said, repeatedly, that you don’t know if the person may have confessed and actually be in a state of grace. But it IS possible to know that a person has committed a mortal sin.

Wrong. I do know what he learned. I either graded or reviewed all of his tests. I was there for his First Communion interview. I know for a fact that he knows that missing Mass, without a serious reason, is a mortal sin.
Yes, in the hypothetical I gave, I DO know. He told me he didn’t want to go to Mass. He consented to missing Mass.
Having some psychological issue is not a release from consent. Does he have the ability to say “yes” or “no” to the sin? In this case, he did.
Yes, you can.
I agree, you rarely have a right or duty to “say” anything. But you certainly have a duty to recognize mortal sin.