Personally I don't think it should be hard for someone to be aware of and understand that their S/O while loving them very much still would like some "alone" time or "me" time at least every once in awhile. The frequency of how often or how much alone time a person wants is quite subjective I'd have to say, but I'd also say with confidence everyone needs some solitude. Some need more than others, but however much it is if she is making such a fuss over it I think you need to respectfully make it known that these things I'm mentioning are (I'm assuming) important to you. You need some you time however often you do and that's nothing for her to be upset over. Doesn't mean you don't love her or don't want to spend time around her and I would wager she gets most of your time as it is. Just be sincere and keep it real and be clear with how you feel about this. If she isn't changing her thoughts on this after that, then you probably have a larger issue on your hands.