Learn English – “If it ain’t in writing it don’t exist” – why the broken grammar

Oh, these work even better with your Matrix reference.

For a single word, try clueless: Lacking understanding or knowledge:

"Oh, for those wonderful days when I was clueless as to my husband's infidelities!"

Then there's unconscious from From Latin un + cōnscius : com-, com- + scīre, to know:

Happily unconscious of the new calamity at home, Miss Pross threaded her way along the narrow streets and crossed the river by the bridge of the Pont-Neuf, reckoning in her mind the number of indispensable purchases she had to make. - Dickens

Incognizant (lacking knowledge or awareness; unaware) is good:

It was with full cognizance of the worldwide melting of glaciers that we rode the telepherique up to gaze down at the glacier at the top of an incognizant world. - Donna Stonecipher

Insensible works:

Yes, cold and insensible Nymph, (replied I) that luckless swain your Brother, is no more, and you may now glory in being the Heiress of Sir Edward's fortune. - Jane Austen

And, asleep:

Now for the first time he FELT that he was asleep and dreaming. - Bram Stoker

Finally, delusional:

I miss labouring under the happy delusion that my life is interesting enough to tweet about.

Here are the three cases you have presented:

(1) I gave Susie a picture of herself.

(2) I went there by myself.

(3) Do it yourself.

I have come up with a new rule under which your three cases as well as the traditional rule are subsumed:

A personal pronoun must be in the form of a reflexive pronoun in order to refer back to another word when both the word and the personal pronoun are contained within a single clause.

I'll call this new rule "the single-clause rule". The single-clause rule surely incorporates the traditional "subject-object" rule, because a subject and an object are contained in a single clause.

Now, let's see if the single-clause rule explains the three cases above.

Regarding (1) and (2), herself and myself refer back to Susie and I, respectively. In (3), yourself refers back to the implied subject you. And these are all in a single clause.