So I often fly transatlantic in business in order to sleep and return in PE when it's a day time flight. I just attempted to buy a new ticket doing this and the outbound business fare was around $4200 based on RT, but when I tried to book the return the PE fare was an astounding $12,000 to complete the RT and even regular economy fare was the same as returning in business, around $4200. Obviously, AA wants you to buy the complete business RT in this case. I hadn't encountered this before and wondered if it's common.

Since the AA schedules and the BA connections were not that great anyway, I finally gave up on AA and booked the flight the way I wanted at a reasonable price with UA.