Brett is not a Brat.

Many of my peers, mostly male just to point out, believe that Brett is a terrible character who can be characterized by another five lettered word that starts with a "b." I disagree, quite strongly. Primarily, there is the problem with the narration through Jake's perspective. No matter how stoic a character he may seem on the surface, he does subtly inject self-sympathy into the story. Jake portrays Brett as a complex, unattainable love interest who plays around and has a lonely life. He loves her, there's no doubt about that, but he's forcing his love for her to take precedence over her love for him. In other words, the readers can see and coo over how much Jake thinks of Brett, but cannot gain access to her thoughts. To them, Brett is a party girl with a sad history and promiscuity as wide and as deep as the sea. In a way, they are correct because she does taken on those characteristics, but on the other hand, they are absolutely wrong.

When I analyze Brett, I see her as a tragic figure. Her true love - one that must have been something to ensnare her - died in the war, and her next love (assuming her first true love wasn't Jake's masculinity because that would just be shallow) cannot provide her with the comfort she needs. She marries the first man, an abusive tyrant, who comes along and suffers terribly. And despite her great looks and lovely personality, she has an inferiority complex. She drinks to cover it up, sleeps around to hide it, and cannot be with Jake absolutely because of it. For Brett, I think, Jake is the perfect man, one who cannot taint a relationship with sex and whatnots. While she is drawn to that idea (as we all are attracted to something ideal), she is too insecure of herself to jump for it. Instead, she finds temporary solace in the flawed guys such as Mike and Robert.

Perhaps my analysis is bias and skewed. That's your opinion. But everyone has their faults, some more obviously than the other. If you are willing to forgive Jake for his inability to communicate his love and need, then you ought to consider pardoning Brett for her insecurities.