When a guy/gal accuses their partner of cheating for no reason, 9 times out of 10 it usually means that they are the ones doing the dirty. Either Ralph was projecting or he was overprotective. I guess the latter is understandable. Nora does seem like a catch and has her head on her shoulders. Ralph was lucky. The woman he actually deserves is Faith.
Nora was definitely the best women Ralph could ever hope to pull. Frankly I'm surprised she went for him to begin with, but she was young, and young people (especially girls) can be manipulated more easily. Compared to Ralph she is a lot more attractive (if she lost some weight even more so), she is considerably more intelligent, she is better educated, she's a hard worker, she has a good job with a future, and she's a caring person who would've supported Ralph if only he weren't so tiresome and obnoxious to deal with.
I can see why he fell for her, why he still loves her, why that love has turned to anger and spite, why he hates himself for screwing up something he will never have again, why he is using another girl as nothing more than something to fill the void and patch up his fragile ego. But he has no one else to blame for his marriage failing. If he wanted to make Nora happy he should've stopped drinking, stayed out of jail, not made the internet the center of his life. Get a job, move to the UK, provide a house for her, give her children.
He just wasn't mature or responsible enough to put someone else first even when he was committed to her. Everything is about him, and if he has to hurt the people closest to him to fulfil his immediate impulses, sobeit.
You reap what you sow; I have zero sympathy.