My girlfriends (28F) reaction to my (28M) coworkers (20-30F) going on vacation without me is making me uncomfortable

I work in IT, and I share a lot of my work experiences with my girlfriend. Recently, due to new management, they've granted every employee an extra week of vacation every year. My coworkers have planned to use up this extra vacation week in March together since they don't get to go on a vacation together often.<br><br>Of course, I didn't expect to be invited and I didn't want to invite myself onto their vacation any way. I've been with this company for about 3 years now and whenever coworkers go on vacation, I always hear about the nice rooms they're staying in, the great restaurants they've been to, the landmarks they've visited, etc. This also applies to me whenever I go on vacation. This is something we all enjoy.<br><br>A few days ago, my coworkers told me they're going on a vacation for a week in March and I thought nothing of it. Just another time whenever they won't be around. But when I told my girlfriend about this, she didn't respond at all. She seemed to just zone out. Days later, she asked me to help her carry something and I did, but after I did, she immediately left for her room and started crying. I tried to ask what was wrong, but she didn't say anything. I tried to ask again and she told me that she just didn't feel good about me being left behind while all my coworkers go on a vacation together. She specifically mentioned that she thought I was friends with them. I tried to explain that I do have professional friendships with them, but that doesn't necessarily mean we're real friends. She then said "I thought you guys were the same as me and my coworkers". I tried to explain that everyone is different. She accused me of being too busy at work and then she just left the house. I tried to explain to her that I'm just an underpaid worker in IT and that most likely, whenever a coworkers tells me something, I have to listen to them for the most part.<br><br>It's been a few days since that's happened and I don't even want to talk to her or see her. She keeps telling me that she's sad that my coworkers are going on a vacation without me. At this point, I just feel uncomfortable. Can anyone please give me some advice?