Why my girlfriend leaves before I wake up everytime she has stayed over?

Me and this girl have been seeing each other for a little more than a month. We get along great and says she wants to be exclusive and we are both happy. However, everytime she has stayed over my place she leaves before I awake. First time I asked she said it's because I snored to loud. Second time stomach ache. Third time I woke at the same time and she said she was just going to go. Fourth time right after sex (excellent sex) she said her stomach hurt and wanted to go home. This was at 4am! She has questioned "what I want" and said she wants to be exclusive and I told her I want that too which I do and really like her. I just feel this is strange and I'm 36 her 29 and never experienced this. Lastly, I'm clean and so isn't my place I'm baffled. Thinking maybe she is hiding something? ? Confused in Minnesota. ..
Why my girlfriend leaves before I wake up everytime she has stayed over?
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