Sketchy-seeming online agent kiwi.com clued me into the fact that, at times, Eur-USA-Eur round trips are cheaper than the equivalent Eur-USA one-way ticket, such that a relative bargain RT can theoretically be assembled with a USA-Eur one way ticket, and then a Eur-USA-Eur round trip ticket for the return back to the USA (discarding the second half of that RT ticket). Hope I've described that clearly. Okay, so checking out such a scenario, Google Flights directs me to United Airline's French web site (conveniently in English, though) to purchase the round trip ticket in Euros. Question is, does United (or any airline that I might be dealing with) care that I actually live in the US and am purchasing the ticket from their French office while sitting in my LaZboy recliner in the United States? I would expect that the ticket would be governed by French/EU contract terms and not by US/FAA terms, but other than that are there any problems that would be likely or possible?