How do i regain my girlfriends trust?

The other day my girlfriend was being nosey and was looking through my phone at my pictures and stuff. But in my contacts there were stars nest to 2 girls that i used to like (one of which i dated) I had just forgot to take the stars off and really it wasnt to big of a deal to me anyway but anyway my girlfriend didnt say anything at first. Then later she brought it up and said i must not have moved on from them and that she lost alot of trust in me. but i really dont give **** about them at all anymore. What can i do to earn my girlfriends trust back?