After finding photographs of them taken while they slept, a honeymooning couple must uncover the truth behind the photographer’s identity hidden in the portraits of previous guests of the holiday home before they become just another picture on the wall.

Are they sexy photos? Is the movie stakes "embarrassment"?? How do they know to look for clues in portraits? Before they become another picture on the same walls where those portraits are? If so, where are they? If they're in public, then they must not be sexy, and the embarrassment stakes are gone, and it's fine if they're up there. If they're in private, nobody else will see them, and the embarrassment stakes are almost gone, and it's basically fine if they stay up there. Also, this is a drama or at most a thriller, but not a horror, not as presented. And "become JUST another picture" sounds stakes-y but isn't, because I'm pretty sure you're not suggesting that if they don't figure out who's taking the pictures they'll literally become a picture?

It's not clear as to who the main character is, but the bigger issue is the why?

Why do they have to "uncover the truth behind the photographer's identity"?

Why don't they call the police? Why don't they leave the holiday home? How do they know that the photos of the previous couples means that they will die? Is it supernatural?

Apart from [ establishing how they know....that if they don't hunt down the photographer, they'll die ], It's an idea worth working on :)

Another take, to EDIT tidbits from --
"After discovering their photographs (on a wall of deceased/in the obituary??), a newlywed must unearth the responsible cameraman (or join his victims)"

Good Luck mikepedley85!!