I think my girlfriend is fucking someone else would be more accurate

This is dumb, but I've got it on my mind so I'm gonna type it out.

Some backstory: I'm in the military (I do nothing of value. Don't thank me) and I got orders to Japan about 6 months ago. I was dating someone at the time and we broke up bc we didn't think it would work with me across the world.

Ffw a month and I'm on Tinder, not looking for anything serious because I was about to move to Japan. However, I met an amazing girl and fell for her quickly. I explained my situation right off the bat and she was fine with being casual for the couple months until I left.

It was fun and we started getting more serious and she wanted to date for real. She said she was fine with doing long distance since I'll be here for a relatively short amount of time. This was great and I was happy. Finally, I fly off to Japan feeling confident in my relationship and excited to see what my new unit was like and exploring Asia. I was pumped. Now, the first month or so was hectic. I was settling in, learning about what I'll be doing out here, and making friends. The time difference made talking to my girlfriend difficult but I was fine. I've deployed before and gone months without talking to loved ones so being able to talk on the phone almost every day way amazing to me.

At first, my girlfriend was missing me dearly and told me how much she was crying bc I'm gone, but she got used to it and I thought we were good. We facetimed and updated each other on our lives frequently. Lately, she's basically gone cold on me. I get a few texts a day from her and they seem just.....uninterested. It kills me. I wish she would either talk to me more or just end the relationship because this is untenable.

I honestly feel like I'm stuck in limbo and can't move forward in life bc of my girlfriend's lack of attention. I want it, but she doesn't feel like giving even a little. I'm scared she's decided a relationship isn't worth it, but just hasn't found the heart to tell me.