Every time my Thai GF goes up country to see her mother, the five days always turns out to be a week at least. There is always a ‘good’ reason for this. Like her dog got run over, or an uncle is sick. She even sent me a photo of a coffin to go along with the ailing uncle. Does this sound kosher, Hillary? Or should I worry?
How long has this been going on? Obviously she wants to be your GF, hence the excuses, but like you, I think she is hiding something. Do not use the services of a PI as they work with the person being spied on, sharing the money you pay as a fee. The best is to ask your maid. She will know if the GF has someone on the side, up in the village. Money better spent than on a PI, my Petal.