A connector assembly, comprising: a connector body defining a plurality of cavities extending longitudinally through the connector body, wherein the connector body further defines a first pair of grooves and a second pair of grooves in opposite outer surfaces of the connector body; inner terminal housings disposed within the cavities, the inner terminal housings being configured to hold electrical terminals attached to electrical cables, wherein the connector body includes flexible primary locking arms configured to retain the inner terminal housings within the cavities; and a retaining device slidably attached to the connector body, having a planar base portion, a pair of compliant cantilevered arms having fixed ends attached to the base and extending from two opposed distal edges of the base, and a terminal retaining wall that extends perpendicularly from an edge of the base and is arranged perpendicular to the cantilevered arms, wherein the retaining wall is configured to partially block rear openings of the cavities, wherein the retaining device allows the inner terminal housings to be inserted or removed from the cavities when in a pre-staged position and inhibits the inner terminal housings from being inserted or removed from the cavities when in a staged position, wherein the retaining device is moveable to the pre-staged position in which latch features at the free ends of the cantilevered arms are engaged with the first grooves, wherein the primary locking arms can flex and the retaining wall is not blocking the cavities, thereby allowing the inner terminal housings to be inserted or removed from the cavities, and wherein the retaining device is further moveable to the staged position in which the latch features at the free ends of the cantilevered arms are engaged with the second grooves, and wherein side walls of the retaining device cover the primary locking arms and inhibit flexing of the primary locking arms and the retaining wall partially blocks the rear openings of the cavities, thereby inhibiting the inner terminal housings from being inserted or removed from the cavities. a connector body defining a plurality of cavities extending longitudinally through the connector body, wherein the connector body further defines a first pair of grooves and a second pair of grooves in opposite outer surfaces of the connector body; inner terminal housings disposed within the cavities, the inner terminal housings being configured to hold electrical terminals attached to electrical cables, wherein the connector body includes flexible primary locking arms configured to retain the inner terminal housings within the cavities; and a retaining device slidably attached to the connector body, having a planar base portion, a pair of compliant cantilevered arms having fixed ends attached to the base and extending from two opposed distal edges of the base, and a terminal retaining wall that extends perpendicularly from an edge of the base and is arranged perpendicular to the cantilevered arms, wherein the retaining wall is configured to partially block rear openings of the cavities, wherein the retaining device allows the inner terminal housings to be inserted or removed from the cavities when in a pre-staged position and inhibits the inner terminal housings from being inserted or removed from the cavities when in a staged position, wherein the retaining device is moveable to the pre-staged position in which latch features at the free ends of the cantilevered arms are engaged with the first grooves, wherein the primary locking arms can flex and the retaining wall is not blocking the cavities, thereby allowing the inner terminal housings to be inserted or removed from the cavities, and wherein the retaining device is further moveable to the staged position in which the latch features at the free ends of the cantilevered arms are engaged with the second grooves, and wherein side walls of the retaining device cover the primary locking arms and inhibit flexing of the primary locking arms and the retaining wall partially blocks the rear openings of the cavities, thereby inhibiting the inner terminal housings from being inserted or removed from the cavities.