Hi Logic, welcome to this little corner of the Internet! I see from your ad you're looking for a bit of fun. Our site isn't really equipped as a dating site, we're a discussion forum primarily. But we also have multiple threads on how to meet people local to you.
Polyamory.com is also more about navigating life when in multiple romantic relationships, not just hook ups, but quite often we get people here who started with an open marriage and then caught feels for their new fuck buddies. It happens quite a lot.
Have you and the Mrs done much reading about navigating opening up?