Fastest and easiest would probably be going to an adult site. Careful though since this usually can lead to some bad feelings. Injecting another in to your intimate relationship could be disastrous.
I would say with a personal ad in your area.
In the midst of all things, tell him or her that you are just passing the time together .
when you are done with each other ?
Nobody EVER said, "I think we should see other people", without having specific other people in mind.
It's one thing I can't do.
Just put a sign in front of your house.
I can be helpful with that.