I think it's ridiculous she left Ethan to begin with. The man dove in front of a car to save his son. So she leaves him for nearly getting himself killed? I mean I can't imagine how I'd feel if something like that happened to my kids but still.... Leaving Ethan was not the answer.
A-are you eating a sandwich!? You're the sound guy! We can hear that! ****! ~ Claptrap
we don't know what happened with their marriage. we have absolutely no idea whether she broke up the marriage or not. in fact, usually with these divorces that happen after a child dies it is a mutual break up.
Actually during the scene where Grace goes to the police station by herself she infers that she and Ethan are just separated and she only left him 6 months ago when he started having blackouts. It still doesn't explain why she would leave her son in the custody of a man who constantly blacks out and she doesn't trust, but it is worth noting that she in fact did not leave him because of Jason's death.
I also thought it was weird in my ending when Ethan and Shaun move into a new apartment and Grace isn't seen or mentioned. You'd think that if Ethan successfully saved Shaun and didn't hook up with Madison then he and Grace would have reconciled.
I do find it horrible that Grace would leave Ethan who suffered horrible brain trauma after trying to save Jason; she appears to blame Ethan for what Jason's death, and for Shuan's kidnapping; then, to top it off, basically told the police that Ethan is the origami killer. Nice ex-wife you got there, Ethan.
You cannot simultaneously prevent and prepare for war. --Albert Einstein