Ya know.. This is how I felt about EB initially.. had her pinned as the penultimate narcissicist (which she may be).
But after studying her social network stuff pretty hard.. my armchair diagnosis would be Borderline Personality Disorder (BPD) primarily -- (sorry, IIRC there's a newer updated clinical name for it - just can't remember what it is).
I think there is one person in this world she would cover up for. It ain't Adam -- and it's not exactly herself, either.
For example.. take a look at her (now deleted) MySpace profile..
http://s857.photobucket.com/albums/...ew¤t=Screenshot2010-10-17at123709PM.png
Notice how under the "About Me" heading at the top of the page, she describes the "one true love" she's ever had as being the person who "made me what I am today"... then invites the reader to request chat to learn more.
Now, note how under the "Who I'd like to meet" heading at the bottom of the page she talks about how she hoped and dreamed of finding her "soul-mate" - and she's found him.
She is talking about two different men here.
Adam is her "soul-mate" -- but NOT the "one true love" she's ever had (that's someone else).
Taking the phrase "made me what I am today" a step farther.. if EB has BPD, it is highly likely that she's lost touch with herself to a point of having become dependent on this "one true love" fellow to define her personality for her.
So, if we theorize for a moment, that the "one true love" may have been an accomplice in disposing of Zahra's body... then turn logic on its head and imagine that it now becomes a selfish (narcissistic act) for her NOT to rat this person out. As her own personality is tied to this person's direction/approval, it almost becomes a matter of mental/emotional self-preservation to refuse to betray the person. Does that make sense? Clinical psych's care to weigh in?
Alert - MY OPINION ONLY - I see where you are going, but when you look back at the volume of bad behavior and multiple relationships, and inability to socially conform in her adult REAL life and her dependency to her "virtual" life, the term Sociopathic Narcissist looks like her to a "T". If she is covering for someone, it is in the disposal only. IMO But, blood is thicker than water, if you get my drift.