The four women who were married to Damien left the palace at roughly the same time, but they arrived at their given destinations at different times.
Originally, Ruyue and Rose were meant to go together, but when she noticed how favorable the location she was given was to her, Ruyue went alone, leaving Rose without any particular assignment.
Now, this was done out of care. Ruyue knew that Rose had no interest in these matters, so she took over, allowing her sister to stay away from battle.
Plus, since she was confident in her power, she felt that it would be unnecessary for both of them to take the time to make the trip.
It could be considered a side effect of the transformation Ruyue was undergoing, but she failed to take Rose's opinion into account.
She unilaterally decided on the practicality of the situation and ignored the emotional aspects related to it. She didn't have an awareness of those emotional aspects anymore, after all.
