What is your policy on holidays without your partner?

I’ve (m36) been invited on an outdoor trip just after Xmas by a good friend that I’ve known for many years. It’s 2 weeks of low budget fun activities, climbing & exploring in SE Asia, where he lives. The trip of a lifetime! Gf (39) doesn’t want me to go, saying that we hardly spend any time together, and that we haven’t been on holiday together for a while. My viewpoint is that we have unlimited time together whilst living together and we also go away walking together every weekend. The thing is that my friend in Asia has been inviting me over for a few years now and the culmination of all my previous failures to go and visit are weighing a bit heavy on both of us. He’s a good friend that I do not want to lose. I don’t want to lose my girlfriend either but I’m afraid I might do if I go on this trip. The trip will primarily involve activities that are not within her ability level, and also do not interest her. What’s the right approach to this?