That doesn't mean you can run off and tell your friends they're perfect for each other. First, consider why you think they're a good match. Do you desperately want to set these two people up based only on shallow characteristics, or is there real compatibility? If you're trying to make a match happen just because they're both gay or both Black, that can be offensive. The potential couple needs to have more in common than that. "Maybe they appear to be a good match because they’re geographically desirable, have similar political views, share the same religion, have a similar sexual orientation, and both love riding bicycles or running marathons," Spira says. "But the perfect match on paper doesn’t necessarily translate to having chemistry IRL." There's no real formula for knowing when people would hit it off, but Spira says the best matches happen when you know both people really well and suspect that their personalities would mesh. So if you're going to suggest a blind date, make sure you're doing it for the right reasons.