The difference is that people in relationships feel guilty shopping around. I know many people with jobs who keep one eye on LinkedIn in case they see a great opportunity.
Which is weird because the great opportunities are based on recommendations almost only. Someone pulls you somewhere, you pull someone to you. You match a friend with another friend in trouble.
I have yet to see (in IT) someone that get great job by the standard interview process.
Also not all persons in a relationship feel guilty of that.
