In the TV series "Mad Men" I'm currently watching, a man is conducting a job interview with two young males (person 1 and person 2) in episode 1 of season 2 ("For Those Who Think Young") starting at about 32:47. During that interview, the following dialog takes place:
Interviewer: "Are you married?
Person 1: Uh, that's why we're on the purpose.
Person 2: He's right. We haven't settled down yet.
Interviewer: [pauses] So, again, you both did everything together, and yet you get paid more [pointing to person 2].
I don't understand this dialog at all. What does "That's why we're on the purpose" mean?
I looked up "purpose" in the wiktionary, but couldn't find anything relevant. And what does this have to do with their pay? Or is the interviewer just changing the topic?
Edit: I should add that person 1 is not a native speaker.