Your coworker was referencing the tiffs. Even though you both have sick chemistry, the tiffs overshadow them. He doesn’t have tiffs with other coworkers. That is why he told you he vibes with them.
Sometimes, the attraction that two people feel for each other is overshadowed by their unwillingness to address said attraction. It becomes a game of who is willing to set their ego aside first and be honest with the other about how they truly feel.
It comes to a head and tiffs occur when both parties refuse to do this even though they both know their chemistry is potent.