You (and the others who downvoted my comment) are completely missing the main point here, which is that the gf is obviously showing behavioural patterns connected to a form of eating disorder, like Anorexia and/or Bulimia.
A woman being upset is not a trap
Of course not. However, a conversation about “being fat”, with a person who suffers from an eating disorder is definitely a trap, as long as you are not a specialized therapist.
viewing relationships as adversarial is setting yourself up for failure
I view eating disorders as adversarial, not relationships. Please stop projecting your incorrect assumptions on me.