My idea, is to do what snapchat does, allow a photo to be deleted after viewing or options for it to be viewed in 24hrs.
Sometimes you post a video or a photo but here u have option to delete but the other party still sees it. Which defeats the purpose of deleting. Maybe having an option to delete photos/videos post in a chat on both sides of the party received, or allow the other recipient to view it for 24hrs or option to delete photos/video after viewing. It would make for a more secure site as well, so if ever hacked, no one has access to those things as well.