She doesn’t have a brother
It seems like the delivery drivers are really getting into all types of odd situations. From asking customers out on dates all the way to helping someone find out their partner is cheating on them. The life of a delivery driver seems to be very interesting, perhaps we should try it out.
So this person was stupid enough not only to cheat on her boyfriend but to order food knowing that there was a chance her boyfriend could find out. She must really have a low opinion of her partner, thinking that he could never put the pieces of the puzzle together in the meantime.