You feel like telling him you're not single in the way that he thinks you're single. After all, you have yourself.
Most people don't get lucky. They get human. They get crushes. This means you irrationally mortgage what little logic you own to pay for this one thing. This relationship is an impulse buy, and you'll figure out if it's worth it later.
I hope to one day co-sign a lease with another person but, well, it doesn't plague me that I have yet to do so. Put it this way: I've never had to violently tug at my own pillow at 2 A.M. to get myself to stop snoring.