I have a feeling AA will fix your reservation, and if you intentionally miss your connecting flight outbound, the rest of your itinerary will be cancelled. Best to get a hold of the airline now and get it squared away.

For similar, search "hidden city". This is an intentional way of procuring a cheaper fare by booking AAA-BBB-CCC when your actual destination is BBB, then just intentionally missing the second flight. In short, it doesn't work on the outbound of a round trip, and also doesn't work if you have checked bags.