There is no there there. I am paraphrasing another poster, but I believe it too. First he was Mom's kid and then her mechanic son, after all she "made it happen" that he went to mechanics' school. She approved of his skater look and hair grease. He was happy being approved of, and Dad was the one refuge. He meets Shan'ann, becomes what he thinks she wants, works, is kind to his kids, affable and obedient to her, calm, capable and nice to his co-workers. Yet so far, no one attributes any particular personality to him, and he cuts off the original Mom's boy Chris, cuts off Mom, too. Then 8 years later he transforms into studly Chris, NK's vision, what he thinks she wants him to be, with the heady rewards of hot experimental sex possibly for the first time in his life. Trouble is, instead of having core values to see him through these different stages, he basically sheds his skin, like a lizard, but emerges as something else, incompatible with the previous persona. Thus in becoming studly Chris he has to shed his current family. (One reason I doubt they had intercourse Monday morning).
This is not rare, I know many ppl who transform partly into their new love interest, picking up hobbies, slang, attitudes, etc. I have even done it myself a bit but without losing my core.
Hard to explain, I don't think there really is a Chris Watts, just whatever shape shift he thinks he should be at a given phase. Now, basically a prisoner with only a bible to approve of him for 23 hours a day, he is transformed into what he thinks the bible wants him to be, and is shedding the old non-religious Chris.
Definitely no offense meant to people who really do live according to the bible's principles.