SPOILER ALERT, at the end...
... why does she decide to fake her own death via that explosion and dental teeth records and also frame William Hurt's character for her murder?
Didn't she, besides getting him to agree to kill her (husband? or lover?), also fall in love with him?
Why couldn't they somehow get together and escape, immorality of their criminal and wrongful deeds, despite (haha) that woman being gorgeous and whatnot (and this film at least wants us to UNDERSTAND the characters and get behind them somehow, even if it doesn't completely excuse their behaviour, and allows audience to make own judgments), notwithstanding?
Many films criminal couples either escaped or attempted to escape. Think of films like Bonnie & Clyde (1967) (SPOILERS, yeah, the police DO catch up with them and SPOILERS, gun them down at the end, but neither of the two people abandon and frame the other) or "Natural Born Killers" (1994) or even in "The Specialist" (1994) where, although they, albeit not legally, killed or one of them did kill BAD guys (Stallone did, mostly via explosives), and the woman (Sharon Stone) was even CLOSE to betraying Stallone's character and endangering his life, at the end, they drove off together as they really fell in love with each other. Or "Basic Instinct" (1992) where Michael Douglas' character and Sharon Stone basically fell in love with each other. And other examples, including the Hong Kong film "Intruder" (1997) with a female and a male criminal duo.
So why does Matty betray him and not somehow get him to secretly come with her, why fake her own death and frame him for her murder? Did she fall out of love with him somehow?