The more I think about this the more I wonder. It's easy to see him as the bad guy. What if *she* was the one pushing him to achieve and go to medical school. She finds out he's never going to medical school and on the same day she miscarries (hence the blood on the mattress). He comes home to find the bloody mattress and realizes she has run away. He doesn't know that he's been set up yet(bloody knife in apartment)and wants to hide the evidence of the bloody mattress so her parents don't see it.
I had relative once who was very good at being little goody-two-shoes and portraying her husband as a bad guy. She forced him to go to dental school and the whole thing just about sent him over the edge. He finally quit and she divorced him claiming physical abuse and sexual abuse. Who knows - maybe they were both crazy.
I don't think she was the one doing the pushing. I think it's because he's from a family of over-achievers (by all accounts) and it left him feeling deficient in the achievement department. So he compensated by making up a stellar life as a top student and soon-to-be doctor. Being exposed would have meant admitting he was an all-around failure, and who knows, Lori might have even called him that.
This is true, but he did lie to everyone about graduating from college. What this before or after his marriage? If they were married when he lied about that, it would bump your theory. She could be an evil witch, and do just what you said she did, and it could explain MH's episode at the motel. Let's wait and see what happens. Anything is plausible at this point.
Your relative and my ex would get along splendidly. I don't want to go into the TMI territory, but unfortunately I have years of experience dealing with liars.