drive a wedge between A and B
drive a wedge between (someone or something)
To cause discord between two people or things. I used to be close friends with Tiffany, but once she started dating my ex-boyfriend, it really drove a wedge between us.
drive a wedge between A and Bmake two people become less friendly or loving towards each other: The disagreements over money finally drove a wedge between them, and they ended up getting divorced.
A wedge is a piece of wood, metal, etc. with one thick end and one thin pointed end that you use to keep two things apart or to split wood or rock.