FWIW, my mom and her husband were booked on the daytime SFO-HKG and early HKG-SFO flights within the next couple of weeks. Bought the tickets long ago and took side-by-side seats on the Upper Deck. Both flights have now gone 74A. CX reassigned them to adjoining seats in different rows rather than seats across the aisle in the same row: now they're in 83A and 84A. Evidently CX too thinks that's the best way for a couple flying together to be seated.