i'm not sure of a free one.. i have looked... and everyone that says it is free, once you spend 30 minutes filling out all the required info and perform a search and want that person's email address-- that's when they inform you that you have to be a paid member to view that info... pissed me off...
good luck!
Just take your girl down to the local gay club on a Saturday and pick up a girl together on the dance floor. Strip clubs are good too, especially couples-friendly strip clubs. Or, visit a local off-site swing party/social and meet a girl there.