Word is that Port, 24, was the one to call it off last Monday (March 9) by phone.
Port's rep could not be reached for comment.
Port first began dating Lyon when she moved to Manhattan to film "The City" and work in the PR department for Diane von Furstenberg. On the latest episode, Lyon revealed that he was going on tour with his band Tamarama, a development that didn't make Port happy.
In a sneak peek video clip of "The City" finale, von Furstenberg gives Port advice on love and when to let it go.
"The City" has already been picked up for a second season, so it's possible that Port will be a single lady when it returns.
Do you think Whitney made the right decision? Would you like to see her single in New York?