Question for the ladies... Help?

I have a habit of asking my wife if she's mad at me whenever she is in a bad mood, because sometimes it's hard to tell when she's mad at me or if she's just frustrated. I love her to death like i would do absolutely anything for her so whenever she's upset i try to fix it and make her happy. Then when she continues to be upset and grumpy then i start to think that it's something I'm doing so i start to feel bad thinking it's me. Then i try to tell her how i feel like i try to explain to her that she's being grumpy towards me it's like i did something wrong. I mean i have feelings too and it hurts when she's grumpy towards me. It's like I'm not allowed to express how I feel?