Reyna grabs Del and JD, holding both by their necks, and Kait must choose to save one of them. If you choose to save Del, Reyna snaps JD’s neck, killing him instantly. The ground begins collapsing, and JD’s corpse falls into a chasm. Del and Kait share an emotional moment together over the death of their friend, and after a short sequence, they meet back up with Marcus Fenix and company. Marcus immediately asks where his son is and is distraught over his death. Fahz shows up with a vehicle to take Delta squad to the next location and starts to crack a joke but quickly realizes what has happened and stays in stunned silence. The game ends with everyone who survived reuniting, and Kait vows to find Reyna.
This ending makes the most sense between the two, as JD’s death serves as a completion of the redemption arc his character goes through during the game. At the end of Act One, JD makes the choice the fire the Hammer of Dawn without proper targeting, causing a ton of collateral damage and estranging him from Kait and Del for the middle chunk of the game. It is also revealed here that he ordered troops to fire on a group of protestors. He comes to Del and Kait’s aid in the desert, and they eventually find a way to move forward as friends. His death completes the arc, since it both spares Del and lets JD die knowing he patched up his relationships with Kait and Del.