<human>: Can you provide a brief overview of the text?

Throwaway here. So my girlfriend often asks me, "Are you okay?" when I'm totally fine or even when I'm actually insanely happy and I could have sworn I was just smiling! It's always kind of bothered me because it always catches me off guard and it makes me feel like I'm giving off vibes that I'm sad when I'm not.  
  
Usually, its not that big of a deal. But then just a few hours ago we were making out after a bath together and I was really excited because I was horny and I wasn't going to see her for a few days since I'm going home for Thanksgiving and I was so ready to get it on. And then out of nowhere she asks me if I'm okay. So this kind of killed my mood instantly because once again I feel like I'm giving off negative vibes and sex was a no-go. Naturally this frustrated me so I tried to explain to her that it was weird for her to ask me that when we were about to have sex (obviously everything is okay!). Well this just seems to make her sad and she just shuts down and won't say a word for a while.  
  
A little while later she opens up a little and tells me she feels like I'm scolding her for caring about my feelings. I tried to explain to her that this isn't the case and I appreciate that she cares about me but then I had to go to work so things still seem a little uncertain.  

Please help! I really really love this girl and I do honestly appreciate that she just wants to make sure I'm happy, but it really sucks that she asks me this all the time when I'm totally fine cause it makes me feel like I can't properly express my emotions. And anytime I try to tell her this she just takes it as a personal insult or gets sad because she feels like she can't ask me if I'm okay. What can I say to her to communicate my feelings effectively?
<bot>: Girlfriend constantly asks if I'm okay when I'm happy or neutral, not sure how to tell her I don't enjoy this without seeming like a jerk.