Why are roundtrip international flights so much more expensive when you are only staying a short time (2-3 days) in the other country?

Question

Title. Why would it matter to the airline how long you’re waiting between the two flights on a roundtrip, even when you’re scheduling both flights well in advance?

In: Economics

Answer 1

I was going to call a little BS on this, but holy crap! I just checked nonstop flights from JFK to Heathrow that arrive in London between 10am and 9pm…

10/21-10/23 $1342+ [Mon-Wed]
10/21-10/30 $573+ [Mon-Wed]
10/28-10/30 $1280+ [Mon-Wed]

What about this:

10/21-10/23 $1342+ [Mon-Wed]
10/21-10/30 $573+ [Mon-Wed]
10/16-10/23 $573+ [Mon-Wed]

I could buy the latter two *roundtrip* tickets only use one leg from each and come out a couple of hundred dollars cheaper than the single 10/21-10/23 ticket!