To Loan or Not To Loan

Me & my bf have been together for a few months. Today he asked me for $1,000 by today. At first he said he wanted $1,000 and to give me $600 back. Basically me just giving him $400. When I said no to that he says okay I'll give you the full $1,000 back. I asked him when would I get it back if I were to give it to him & he gave me a vague answer of "a few weeks". I don't have THAT much money and definitely not enough to where I would be okay with not receiving that $1,000 loan back. I'm in the process of starting my own business & investing a lot of money into that. Which btw I asked him to help me financially with it months ago when the pandemic hit. He said no and basically told me to get a job. A part of me feels guilty for saying no but like at the same time no part of me thinks it's a good idea to trust someone with that much money.