Ẓalaʿat evokes limping or impaired movement, while zāgha indicates swerving from the right line. Qiwām denotes the principle that keeps a thing upright and sound. Together, they turn an unstable relationship into something visibly staggering.
Idhā introduces a contingent situation. The sentence therefore combines a norm of generous conduct with the possibility of disengagement when the supporting structure of the bond no longer holds.