Options would seem to be:-
Change the country on your Apple ID - Unless you live in Thailand then I wouldn't do this in case as I think you're the restricted as to when you can change it back (It's not like you can flip-flop).
Create a new Apple ID, log in with it, download the app, then log back in with your normal AppleID (This was the way I did it).
Get your GF to log into your phone with her AppleID, download the App then log back in with your own ApplID
Get the GF to install the App on her phone (Apple or Android) & use the app on there