Europe to U.S. Oneway ticket bought in U.S.

[diegopdl]

Hello,

i'm curious if anyone knows what an airline can do if their restrictions states that if a oneway ticket is purchased in the U.S., there has to be an outbound flight from the U.S. in the first place

The reason I ask is that my wife who is a student in italy, is flying over from Europe on Lufthansa to the U.S. on a oneway. I found an inexpensive ticket over here in the U.S. but the travel agent told us that they require a flight to have originated from here. This may sound confusing, but essentially, I want to know how much they enforce this rule. She has all the proper documentation to enter the U.S., so I don't see why they'd stop her or give her any problems?