Did Jesus correct Moses?  It is entirely possible that Jesus had other conversations that never got written down that "clarified" what he meant regarding marriage.  We don't know.  I think it is inconsistent with everything else we know of Jesus to assume he would require someone to stay in a loveless marriage, or with an abusive spouse, or even deny a person the gift of another love when a marriage fails.  

Those few words have been taken as if they constitute some never-to-be-questioned absolute.  Jesus also said "Call no man 'father'" and, yet, we are taught to call priests "father."  Some picking and choosing going on here and there - this has always been true.