Am I overreacting?

So, my boyfriend never says goodbye. He's been doing this since before we were together and with everyone he knows. For example, if he's with a group of people he doesn't announce that he's going to the bathroom or even that he'll be right back, he just gets up and leaves. But It's not just to go to the bathroom, it's every situation. People have made remarks to me about how abrupt he is and we laugh about it. But he does it with me too.

Today, we were working together on the same computer for a project at school. We were talking, it wasn't like we were working separately. We decided it was late (it was like 11pm) so we pack up. He's faster because he has less stuff. He walks out the door, doesn't say anything to me, doesn't look at me, and I think he's going to the restroom, so I sit back down and wait for him. I've been waiting a while, so I call him. He's in his car driving home. He's already walked all the way across campus in the dark to his car (which I'm now going to have to do alone) and I've just been sitting there waiting for him.

I know I'm stressed out about school right now, but he does this all the time. Like, we'll be talking and he'll just leave, or he'll just hang up if he thinks the conversation is done. If we're walking somewhere together or shopping in the grocery store, he doesn't wait for me, he just walks and expects me to run to keep up or something. And, Idk, it hurts my feelings or something? It doesn't feel good, it feels like I don't have any weight on his life or something. Like I don't matter enough to say goodbye to.

Am I crazy?

I've talked to him about it before, and he doesn't see the problem. I have tried talking to him about social cues and what his actions are saying, and he just said, "if I have something to say, I say it." I got angry about tonight and he just told me that every time I get stressed I find something to be mad at him about, and maybe that's true but I really want his behavior to change. I feel dumb and like he's right but also I'm crying, lol. My parents live so far away and we never talk, so he's my only family.

If you think I'm overreacting, please tell me. If you think I'm right, can you help me find a way to explain to him why it feels so bad?