I(27m) got invited to a boys weekend and my girlfriend (27f) says she can’t be away from me for that long. What can I do/say to assure her that everything will be fine?

A couple weeks ago my boss invited all of his employees to come up to his lake house for the weekend. It's about 2.5 hours away from where I on-line. My girlfriend keeps saying that she doesn't want me to go because she can't be away from me for that long. We have been together for almost 4 years and in that time have only been apart for 4-5 days because of a bachelorette party 3 years ago. I keep on saying that everything will be okay and that she should make it a girl's weekend. I just don't know what to do, I feel like I can't be my own person anymore and I don't know what to do to be able to go on this trip.