Connector and a connector assembly

A connector assembly, comprising:

• a first housing including a receptacle and a first terminal fitting;
• a second housing having a second terminal fitting and being fittable into the receptacle along a mating direction for connecting the first and second terminal fittings;
• and
• a retainer mountable on the second housing along a mounting direction aligned to intersect the mating direction, the retainer being configured for locking the second terminal fitting in the second housing, wherein:
• the retainer comprises at least one fastening section for locking the respective terminal fitting when the retainer is mounted at a complete mount position with respect to the second housing, and at least one interfering portion for interfering with the receptacle when the retainer is stopped at an incomplete mount position before reaching the complete mount position, the interfering portion having at least one guiding surface aligned for guiding the interfering portion into the receptacle when the retainer is at the complete mount position,
• an introducing surface is formed at least partly around an inner peripheral edge of a leading end of the receptacle for introducing the second housing into the receptacle, and
• the interfering portion is formed with at least one contact surface offset from the guiding surface in a direction transverse to the mating direction, and at least one receiving surface at a position of the inner peripheral edge of the leading end of the receptacle substantially corresponding to the contact surface, the receiving surface being offset from the introducing surface and being disposed and aligned for achieving substantially surface contact with the contact surface when the retainer has not reached the complete mount position.