Do I have a right to be upset?

My grandfather just passed away earlier in the day from cancer. I wouldn’t say we were super close but we were still somewhat close and I’m very upset over it. My boyfriend and I have been dating for a while and he knows about my grandfather’s passing. He’s always very supportive and there for me when I need him. Today we were talking about plans for tomorrow and he told me he was going to his friends house after work which normally I would be completely fine with but it kind of rubbed me the wrong way since I want him to be there for me because I’m upset and don’t really want to be alone. Do I have a right to be upset about this or am I being selfish?