A connector assembly comprising a first connector and a second connector, wherein: the second connector is mateable with the first connector along a front-rear direction (X-direction) under a state where the first connector is located forward (positive X-direction) of the second connector in the front-rear direction; the first connector comprises a first inner structure and a first outer member; the first inner structure comprises a first connector body; the first outer member is attached to the first inner structure; the first outer member has a first lock surface and a first abutment portion; the first connector has a first regulation portion; the first lock surface faces forward; the first regulation portion faces rearward (negative X-direction); the first abutment portion faces rearward; the second connector comprises a second inner structure and a second outer member; the second inner structure comprises a second connector body and a second abutment portion; the second connector body is connected to the first connector body under a mated state where the first connector and the second connector are mated with each other; the second abutment portion faces forward; the second outer member is attached to the second inner structure; the second outer member has a second lock surface; the second connector has a second regulation portion; the second lock surface faces rearward; under the mated state, the second lock surface faces the first lock surface in the front-rear direction and regulates a rearward movement of the second connector relative to the first connector; the second regulation portion faces forward; the second regulation portion is configured to face the first regulation portion in the front-rear direction and regulate a forward movement of the second connector relative to the first connector under the mated state; the first regulation portion and the first lock surface are apart from each other by a first distance in the front-rear direction; the second regulation portion and the second lock surface are apart from each other by a second distance in the front-rear direction; the first regulation portion is located forward of the first lock surface and the first distance is longer than the second distance, or the first regulation portion is located rearward of the first lock surface and the first distance is shorter than the second distance; and the second outer member is configured to be movable relative to the first outer member along the front-rear direction under the mated state, characterized in that the first outer member has the first regulation portion; the second outer member has the second regulation portion, and the second abutment portion is brought into abutment with the first abutment portion when the second connector is mated with the first connector. the second connector is mateable with the first connector along a front-rear direction (X-direction) under a state where the first connector is located forward (positive X-direction) of the second connector in the front-rear direction; the first connector comprises a first inner structure and a first outer member; the first inner structure comprises a first connector body; the first outer member is attached to the first inner structure; the first outer member has a first lock surface and a first abutment portion; the first connector has a first regulation portion; the first lock surface faces forward; the first regulation portion faces rearward (negative X-direction); the first abutment portion faces rearward; the second connector comprises a second inner structure and a second outer member; the second inner structure comprises a second connector body and a second abutment portion; the second connector body is connected to the first connector body under a mated state where the first connector and the second connector are mated with each other; the second abutment portion faces forward; the second outer member is attached to the second inner structure; the second outer member has a second lock surface; the second connector has a second regulation portion; the second lock surface faces rearward; under the mated state, the second lock surface faces the first lock surface in the front-rear direction and regulates a rearward movement of the second connector relative to the first connector; the second regulation portion faces forward; the second regulation portion is configured to face the first regulation portion in the front-rear direction and regulate a forward movement of the second connector relative to the first connector under the mated state; the first regulation portion and the first lock surface are apart from each other by a first distance in the front-rear direction; the second regulation portion and the second lock surface are apart from each other by a second distance in the front-rear direction; the first regulation portion is located forward of the first lock surface and the first distance is longer than the second distance, or the first regulation portion is located rearward of the first lock surface and the first distance is shorter than the second distance; and the second outer member is configured to be movable relative to the first outer member along the front-rear direction under the mated state, characterized in that the first outer member has the first regulation portion; the second outer member has the second regulation portion, and the second abutment portion is brought into abutment with the first abutment portion when the second connector is mated with the first connector.