For Flights overseas, is there a way to book outbound and return separately?

[m61376]

I know domestically and to the Caribbean it’s easy to book one way tickets, but I’m finding one way more expensive than round trip NY to London. Is there a trick?
There’s great availability on the outbound flight using miles on AA, but the return flights available with miles won’t work. I wouldn’t mind using miles and paying for the return.
Any guidance would be appreciated.
Thanks

 

["Roger"]

You won't be flying back on American, but there are some extremely low to somewhat low prices one way on Expedia. The lowest fares are on the off-beat airlines like Norwegian Air.