Jon Hamm's girlfriend wants to marry him.

Jennifer Westfeldt, the 'Mad Men' star's partner of 14 years, recently issued him with an ultimatum that they marry or break up but Jon refused.

A source said: ''Jon and Jennifer have talked about marriage before but he's always shied away from it. Now Jennifer is at a stage in her life when she wants stability, security and a family. So she worked up the nerve and told Jon it was time to get married or she was moving on.

''Jon angrily told Jennifer that a wedding was not in their future. He said 'If you want to get married, go right ahead. There's the door, go find someone else to marry because it's not going to be me.' Jennifer was devastated. She broke down in tears and Jon stormed out.''

Friends believe 41-year-old Jon's fame since starring in 'Mad Men' has made him more determined than ever not to settle down.

The source told National Enquirer: ''Jon's like a kid in a candy shop these days and he made it clear that he doesn't want the party to end. Jennifer backed down but now she's miserable.''