That was the life and death kiss and you only know a long time afterwards what it is, the life and death kiss. (III.5.8)
Antoinette describes her last kiss with Sandi Cosway. We never really get to know Sandi in the novel, but in the few instances we do see him, he seems to be a presence that offers Antoinette security, safety – well, happiness, really. So why didn't she run away with him?