What Do Episodes Of Memory Loss In A Person Indicate?

Hi i hope you can help me im writeing on behalf of my girl friend. since we got togeather i noticed somthing strange that would happen about once a week but might be more but i dont know becuase im only there half the week.out of no where (like a switch) she will start to repeat herself sometimes over and over and its litrally because shes forgot shes said it and theres a look of compleat confusion. The way she looks and talks i can tell instantly shes haveing one of the strange turns. I can even tell over the phone . Last night i could tell she was like this at 1 point we drove wiv her dog to her mom and dads as her kid needed somthing so she went in with the dog 2 mins later returned without the dog because she forgot the dog was even with her. Slightly later i said im off to the shop do u want anything she sed no i went to the toilet first then said bye then she then replied where are u goin i said the shop ive already told u this she replied ok so can u get me a choclate bar i sed ok i went and returned in no more than 10 mins i walked in she said where u been i said the shop and i got u sumthing she looked happily surprised and said what u got me i said what u asked for. I said do u remember what that was her reply was no. This continued for the rest of the night its hard to even explain to her whats going on i hope u can shed some light on this plz thank you x