Is AUTHOR wrong in the post ? POST : This happened last week and has caused some bumps with me and my girlfriends relationship. 

My girlfriend (F16) lives in my home state, however, I (M16) live all the way across the country because I am going to school. I came back home this past week for the first time in two months and I was finally able to spend time with my girlfriend in person. During this week I saw her many times. However, when it came to when I had to leave on Monday, the only time I could see her before I left was on Saturday. Other than spending that last night with me, she decided to spend it going to a party. She invited me to come, however, I decided not go because parties are not my thing at all. I did tell her that I would like to spend it with her because this will be the last time I will see her in around a month, but she declined because she said she's had this party planned for weeks (I did not know she had this planned, she only let me know the night before). After she went to the party, I told her that I was really upset because I really wanted to spend that night with her. Her, on the other hand, was upset with me because she feels like she shouldn't have to devote her whole week to me. I get that she has her plans, but the time, the time that I have to spend with her is very limited because I live so far away. 

So am I the asshole for wanting to spend time with her before I leave despite her plans?

TLDR: Girlfriend is upset that I wanted to spend time with her before I leave for a month, despite her plans made weeks beforehand that she only told me a day before. 