Hi, I guess no situation is ever simple.  My gf about six years ago got pregnant by a thai man.  He was younger than she was.  He may have slipped her a date rape drug...but be that as it may, her parents required her to get married to the guy (buddhist? ceremony) BUT told her not to file the marriage with the local government.

NOW I come into the picture.  I'm thinking about buying a house and she will be on the title.  From what I read, the marriage is not legally binding since the marriage paperwork was not filed with the local government authorities.  Will the ex-husband/boyfriend be able to attach the house once he finds out about us?  She has been separated from the man for about 4.5 years....

Any advice is welcome...

Simple, see a good Thai lawyer and protect yourself (and her). A small investment now could be worth it.