My girlfriend (F24) says I (M25) can’t be upset

My girlfriend (F24) is studying to be a public servant. She made it clear before we started dating that this was her priority and that I (M25) would come second, and I respect that.

At the beginning, we agreed to study together every day so we could spend time together. But last month, she said that having me there was distracting her and that she preferred to study by herself, which is fair. We were also sleeping over at each other's places every other night to see each other during the week. Again, this week she said we couldn't anymore because she decided to change her schedule and wake up earlier. I understand that too.

I asked her if she wanted to go out Friday night, and I also invited her to my uncle's birthday party on Sunday so we could see each other this week. She said Sunday was fine, but on Friday she had her uncle's birthday so we couldn't go out. I was kind of hoping she would invite me (I've already met all of her family and we all get along).

By chance, it was also the birthday of a friend of mine, and he happened to invite me last minute. Once I arrived, he asked me where my girlfriend was and suggested I invite her too. So I did. At first, she agreed to come after her uncle's birthday, but then she changed her mind again because her cousin said the party location wasn't a nice place. Again, I'm fine with her not wanting to go, that's her right. But after I got home, I got a message from her telling me that I better not be angry about her not going, because that would create an "useless argument" and that just made me upset.

It shouldn't matter if I have a reason to feel a certain way or not. I have the right to feel however I want. I wasn't even angry until I saw that message. Now, I feel hurt and frustrated about the whole situation. Should I confront her about it?