From someone that’s been on both sides- She may think she’s helping you think things through. The fact that she’s thinking things through enough to HAVE complaints or worry shows she’s probably trying to see this idea fully formed in her head. There is a difference between trying to break it down and being negative. You both may need to look into different ways of communication so you both feel heard. And you might want to think about what she’s bringing up. She might just have good insight if she is actually trying.