if you leave without a backward glance, you are completely happy to leave and have no sad feelings about it.
She left the city she had lived in all her life without a backward glance.
without a backward glance
Without any reservations, remorse, or regret. Often used to describe leaving a place or situation. Likened to literally leaving somewhere without turning around to look at it one last time. I could leave this town without a backward glance—there's no reason for me to stay here.I thought he really loved working here, so it was strange when he up and resigned without a backward glance.