She thinks (and is mostly right) that she marries an ATM. The social values of a Thai compared to a Caucasian is mostly diametral but the Caucasian does not realize this most of the time and if so, it is too late.
Many of these girls got bonked as teenagers on the social behest of the grannies and uncles to marry (not legally but just traditionally with lots of Sinsot/Dowry) and then carry on and produce offsprings. Testosterone-loaded boys hammer to no end until "Bingo" and she's pregnant. Boy makes a runner, is legally not bound and is not taken to the cleaner for child support as he is busy impregnating the next sweetheart in another village and has no money to start with. In addition the loss of face of the pregnant girl's family is not to be overlooked as well.
That explains, why each and every department store must be having tens of thousands of cashiers on the payroll and, my boy, those paychecks are fantastic as they result in gold necklaces the size of a huge motorbike chain, the brother gets a motorbike and daddy if not uncle roams the village in a pick-up. Mama sees some gold as well and everything seems to be restored. The cold truth is, that the girl plies the trade of "les belles de nuit" which she shares with hundred thousand other girls. Irregular payments to the village for the offsprings upkeepinig, frequent hair dressing, lots of alcohol and other pops, gambling and the notorious boyfriend-cum-motorbike-delivery-boy ensure, that the bottomless pit stays bottomless.
Comes along Khun Farang from faraway lands, funny language and funny food, but who cares. Off she goes to farangland, no sanook, but far away from all the misery and all those people leeching off whatever they can. The farang usually has a story of his own being divorced with some kids in the ex's custody and life is miserable as well. Ideal fertile ground for such relations. It usually works though only, if the farang does not have too high expectations or is not the sharpest tool in the box.
In most cases it does not work in the long run. He met the girl in a bar and fears that whoever spills bigger banknotes will take over the bounty. She, on the other hand, does not trust Khun Farang either as he paid/pays for her. If he finds a better deal - not essentially financial alone - then she's past history.
Vicious circle indeed; and if he's a tourist living outside Asia, then he will learn pretty soon, that you can take a Thai out of Thailand but you cannot take Thailand out of a Thai.
You're welcome!