V vremya etoi istorii tol'ko smert' mogla godno konchat' brach. Ideya ubit' Ivana prishla ot Lizaveti.
Posle rozhdeniya svoi docheri, dorogovo ploda eyo matki, Lizaveta dumala, chto bilo pravoe vremya konchat' brach, potomy chto ona dostugnula eyo glavnuyu mishen'.

At the time of this story, only death could acceptably end a marriage. The idea to kill Ivan came from Lizaveti.
After the birth of her daughter, the precious fruit of her womb, Lizaveta thought that it was the right time to end the marriage since she had acheived her main goal.