Because of Facebook's confusing privacy settings and, let's face it, blatantly predatory relationship with their users, the site provides you with a wealth of information about all your old high school friends. Simply hire some high-level hackers to attack someone's Facebook profile, and they can easily learn anything about their private life you want. If you're doing this on the cheap, then you can probably figure out their daily schedule, roughly -- when they go to the gym, when they get off work, their primal fears.
Learn to see committed relationships as the thermal exhaust ports in the Death Stars of our lives.
The next step is simple: Appear at those places, dressed in the most expensive clothes that you just bought for this very occasion and then washed twice to make it look like it ain't no thing. "Oh, hey Kevin," you'll say, shortly after ordering some weird, made-up coffee like a macchiato, "Funny seeing you here. Yeah, I just got back in town a few days ago. I'm here on business." No need to specify what kind of business, I'm sure they'll remember.