If you discover someone that you are attracted to, physically and emotionally, then you can ponder the best means to form a relationship with her. Until then, you will necessarily enjoy the company of women who see men in the same light, as a temporary amusement.Expats dating Indonesian girls are numerous, and many will find that though certain aspects of their relationships are much easier than with a western girl, there are also some difficulties that men need to take seriously if they want to be successful.
The situation faced by many expats is that they don't mind paying, because they understand that the girl cannot afford some expenses that are clearly part of the "expat lifestyle".
If you find yourself in this kind of situation, I think you need to convince your girlfriend that the best you can do is "fake" the conversion to become Muslim in order to look good in front of her family, but keep your own religion without telling people except her.
If you are not ready to do that, and if she doesn't understand it as well, then you should find a Christian or Hindu girl, they make up 10% of the Indonesian people so it's not that hard to find.
If you are catholic and no ready to adapt, then you will have some troubles finding an Indonesian girl who suits you.
Even if she is not that religious, chances are her family is, and they will not tolerate anything but a Muslim wedding.