Well, she is kind of married to him. Not a lot of other people who would break his heart.

Of course, Stephen (the character) is an egotistical jerk, who so far in this story has made a life-changing decision without telling her, tried to foist the responsibility off on her, and shouted at their kids, all without ever apologizing or considering that someone besides himself might have feelings. You really can't blame character!Evelyn for calling it quits.