Look — there are all kinds of reasons for this random girl to send naked pictures to your boyfriend, but rather than focus on why this girl sent the photos, you need to focus on why he’s saving them! 😳
Since you’ve been together for two years now, it might be a good idea to tell him that you’re hurt that he saved those photos, and if he wants to see a hot, naked girl, you’ll give him one to look at (in you!!). 😎 Don’t come at him in a way that will make him feel defensive. Instead, approach him with your feeling hurt (not angry) and your interest in being that naked girl he wants to see.
Let me know if that helps.