It's hurtful to lead someone on in a relationship.
Mary  has been dating Fred since high school but lately she has also been interested in a guy she works with.
Mary wants to explore new relationships.
Mary tells Fred she wants to take a break and see other people.
Mary asks her coworker out but wants to keep seeing Fred incase her new relationship doesn't work out.
Fred agrees and the two part on good terms.
Fred finds out about Mary's coworker and causes a scene at her job which gets her reprimanded by her boss.