NYC Apartment renting restrictions/laws?

My girlfriend and I are trying to rent a one-bedroom apartment in Manhattan and are having trouble dealing with the rental agency restrictions. We are an unmarried couple with a combined income around $70K and the apartments we are looking at are between $1600-1800/month. Each agency we've met with says that as an unmarried couple we cannot combine our income in this way. So they told us we each need a guarantor who makes about 80xtimes the monthly rent- but we do not have 2 guarantors to meet this condition. One of these apartments this happened at was an apartment for $1750/month, I told him we do not have 2 guarantors and we both want to be on the lease, so instead of having a guarantor--what if I prepaid you a full year's rent on a 1-year lease $21,000 in cash up front? The guy said that the rental agency won't do that either? WHAT THE HECK...and this same thing happened with another broker and management company. Does this sound strange to any one? How do we, as an unmarried couple, get an apartment together in NYC?