AA award ticket for Cathay Airlines

Hi all! I’m trying to plan my honeymoon to Bali and have lots of American Airlines miles. I just tried to book DFW-LAX-HKG-DPS, which uses Cathay Airlines for the last two legs. AA says I have to pick seats through Cathay Airlines. In chatting with a Cathay agent, I was told I can’t upgrade even if I pay or pick my husband and I’s seats until check in. Because I have status she said I can pick my seat now, but not my husband’s. Does anyone have any suggestions? He’s a nervous flyer so I don’t know if I should just cancel the ticket and pay out of pocket so I can guarantee I can sit with him. Thanks for any feedback!