Keeping him thinking of her as they are out.
Pegging can only happen within Devotional Sex if it is something that the Knight is willing to do and if his Princess decides to do it.
Perhaps this is her fulfilling her fantasy (and he is just willing).
Or perhaps it is his fantasy and she is finding that she enjoys it as much as he does.
Either way, as her smile shows, when both are devoted to the other pegging can be enjoyed as a shared sensual experience. What fun!
Giving him a visual tease.
Though he is hungry for her, she will wait until she is ready for him to enjoy her pleasures.