Work Permits differ from Employment passes in that they are for people in low-income jobs in Singapore eg. domestic workers (maids), labourers on construction sites etc.
Anyway, many people who are in de-facto relationships manage to get a Dependant's Pass. YOu normally need to get your country's embassy to write a letter to say that they recognise common-law/de-facto relationships. You need to back it up with proof that you are in a stable relationship eg. joint bank accounts, rent/mortgage payments in both names, joint names on utilitiy bills etc. Speak to your embassy - they've probably handled lots of cases.
