DEAN: Wait a minute. I thought we were gonna spend some time together.
RORY: We are.
RORY: I don’t know. Tomorrow maybe?
Rory and Dean now enter their third serious fight together, in a relationship which has only lasted around six months.
You can definitely see Dean’s point of view. He wanted to spend the day with Rory, but she was busy (and didn’t tell him about that beforehand), so they agreed to spend the evening together instead. But when he turns up for that, Rory tells him that now she has to spend the evening alone, planning her future. When he asks when he can see her again, she’s not sure and says the next day – maybe.
Dean is right that Rory is dismissing him from her life as if he doesn’t matter, and he is also right that her behaviour is absurd. She can’t possibly catch up on all the volunteering she thinks she has to do in one night, and she can’t even organise volunteer work for herself on a Saturday night when everything is shut. She possibly has an hour or so to make calls, and then she could spend the evening with Dean.
On the other hand, Dean is clearly jealous of the time Rory spends away from him, and makes very little attempt to understand Rory or help her feel less stressed out. If Rory had perhaps been more honest with him from the start as to how much of her summer would be taken up with classes, homework, and volunteer work, rather than springing it on him as it happens, he might have taken the news better.