Am i weird for being upset about his trip?

I've been with my boyfriend for 8 months, long distance relationship, different countries in Europe. We see each other once a month, mostly me going to see him since he is working and I am still at university. He decided to go on a trip for a week with his best friend instead of visting me and it really made me upset because he can see that friend whenever they are not working or after work but he can only see me with vacation days that he is going to use on the friend. I don't mind him hanging out with the friend but he can genuinly see the person whenver and he cant see me whenever. If we were in the same country or living together, I wouldnt mind him going on a trip either. Just the fact that those vacation days are the only way to see him and he is deciding to spend it on someone else makes me feel upset.

He knows how i feel about it. I don't want to tell him to cancle the trip because of me either but I just feel so shitty about this.