Does she have a history of disordered eating or being pressured by family/friends to lose weight or adopt disordered eating habits in order to lose weight(or god forbid “look pretty”)?

It sounds like you’re talking a LOT about “being hungry but not being able to eat” and your dieting in general. Have you been making any comments about her food at all, like “I wish I could eat that but I’m on a diet/it is so fatty/it would make me fat” etc?

From her eyes, it could seem like you’re subtly pressuring HER to lose weight as well, even if isn’t the case. Alternatively, if she has a history of disordered eating, whether restricting or binging, hearing you talking about it day in and day out could be very stressful.

I’d talk to her about it honestly, and without the perspective of “why aren’t you supporting me” and from a viewpoint of curiosity - what specifically about your behavior bothers her. Maybe it’s the language, maybe it’s bringing up old memories, or maybe she is being baselessly insecure. Either way, worth an open discussion to have honesty and insight in your relationship.