Even after ending their personal relationship, Mitchell Gold and Bob Williams kept their business partnership—and friendship—intact. That decision, and the mutual respect that undergirds it, still defines their brand 30 years after they founded it together.

For every business rule Bob Williams and Mitchell Gold have successfully broken, perhaps none is as outrageous as this: Nearly two decades after ending a 15-year romantic relationship, they remain professional partners to the mutual benefit of both—and the company they created together.

Anyone who has ever worked with a significant other knows how hard it can be to finesse that delicate balance. But Gold and Williams have accomplished the rare feat. “It’s easier now that we’re not together,” says Gold, who usually does most of the talking—an arrangement, by that way, that still suits them both just fine. “After we decided not to be life partners, we decided to still be best friends.”