So I potentially have an update. Nothing new in terms of conversation, but some information that may or may not be relevant that I didn't really think about before this.
I just spent some time talking to a good friend of both of ours that has known us both since before we started dating, and she brought up something that I also briefly mentioned to my girlfriend that I probably shouldn't have let be dismissed so easily.
What if there is some sort of prevailing mental health issue here? I don't mean to trivialize in the sense that I think, "because she wants change something must be wrong", but the signs are there. She enjoys being there so much because of family and because of the support she gets. Here, the support isn't there from anyone but me. Her home life isn't the greatest, without going into too much detail, and there are issues there. So when she goes back to Portugal, those issues disappear and suddenly she is showered with support from a dozen people that she only really receives from me and a few close friends here.
I brought up the idea of seeking help, talking to a professional. I did this early on in the stages of our conversation yesterday morning. Our mutual friend then independently also suggested that as the very first thing to do in her talk with me. My girlfriend is adamant that it isn't that kind of issue because she doesn't feel it that way and just feels better there, but I don't think it could make it worse, could it?
The issue now, though, is that I feel like I'd have to backtrack if I was serious about this. To go from, "Hey, I'll try this out", to, "Hey, maybe you should talk to someone before we make any decisions", is going to feel like I've changed my mind about things and don't believe what she believes she's feeling.
Overthinking.
Just do it man, your life can either be interesting and different or dull and safe. You don't get to have both, and the opportunity to explore the former comes up like maybe a max of 5 times per lifetime. If you have a good head on your shoulders you can make it no matter where you end up. ---