Generally speaking, I don't encourage a foreigner with only 7k income for 2 adults to stay in Singapore unless you are really here to live like a pauper and squeeze every single cent into savings for a better future back home.

You never say where you are from. If you are from a developed country and expect to maintain similar decent lifestyle then I can more or less guarantee 7k will never work out for both of you. If you are from a developing country with much lower living standards compared to Singapore, in theory you can push down your lifestyles to the lowest possible and still have some savings to send home.

But I reckon there won't be much left, maybe S$2k at max every month. However this will literally require both of you to just eat cheap, work and sleep every day. Not sure how long most people can last like that.