7 Days: why Calvin suddenly treats Christie so badly.

More throwing out ideas to Calvin sudden change of behavior towards Christie.
As to the terminal illness route
Steven said he looked up materials on Vivien Leigh for inspiration in this role-- and that truly stumped me then.. why VL? But now I wonder if maybe Calvin is inflicted with a degenerating mental sickness that passes from generation to generation. (VL suffered mental sickness towards the latter of her life, specifically afflicted with manic-depressive episodes) So when Christie brought up her urge for babies and a future with Calvin, he flipped. (Maybe he cannot subject Christie or their future child/ren to what he and his mother had suffered through his father's crazy episodes.) Just throwing out ideas. 

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I'm still confused as to how the series will resolve all conflicts and wrap up neatly with a "all's well that ends well" ending.

Came up with all these scenarios concerning the diamond.

Episode 14, Calvin tells Judy the diamond is fake, that he has lied; but I think otherwise. If the diamond is fake, with her experienced eye, Christie would know, so I think it is the real diamond. Speculating Calvin's strategy:

1) I am convinced that Calvin's motive is not to steal the diamond, but something else. If his plan goes awry, Judy will be accused as his accomplice because the diamond is in her possession, but he knows the charges against her will not stick because her past and alibis will prove her innocence. And the police will be no wiser as to Calvin's partner in crime, so Christie is safe from implication.

2) Or if his plan is successful, and he escapes scotfree before the Chuis discover that their diamond is missing, Judy will be the one implicated not Christie.

Either way, Christie will be safe from any implications.

Calvin's eyes, that very windows to one's soul, belied his outward mistreatments of Christie. In epi 13, watch how Calvin's eyes, against his will, surreptitiously tracked Christie's movement when she leaves the pool with Ah Lung, or in epi 13 how his eyes mirrored his sadness and melancholy.