"I had followed my girlfriend in Australia."
Translation:Εγώ είχα ακολουθήσει το κορίτσι μου στην Αυστραλία.
to avoid any misunderstanding, I would never call any female friend of mine "φιλενάδα" unless she is my "girlfriend". Any female friend of mine is "η φίλη μου". But here DL is using the term "κορίτσι μου", which can also mean "κόρη μου" in its appropriate context: Έχω δύο παιδιά, ένα αγόρι και ένα "κορίτσι". Το "κορίτσι" (μου) ζεί στην Αυστραλία. Bottom line: I think that for this sentence DL should accept φιλενάδα/κοπέλα/κορίτσι, but the first word that comes to my mind for "girlfriend" is "φιλενάδα"
The word you use depends sometimes on regional or age-related reasons. I think this is such an occasion. I live in northern Greece and my surrounding here uses κορίτσι for girl or girlfriend, κοπέλα for girl or girlfriend and φιλενάδα for girl (in northern Greece usually girls call other girls φιλενάδα). However, I haven't lived for a long time somewhere else except Macedonia and Thessaly and I cannot be absolute.
Anyway, I have added φιλενάδα as alternative and I'm very glad for this constructive debate :D