Dear Steve and Samantha,
You can’t determine how your friends respond & react to their losses and you cannot dictate how long they can mourn their loss. There’s a limit to which you can get involved in someone’s life. So, you are bothered because your friends still display the pictures and write about their dead loved ones. It’s permissible if only you’re bothered about their mental health as against “fighting” them for choosing how they reacted to the passing of their loved one. I hope you know what Post-Traumatic Stress Disorder is? Be empathetic for God’s sake. Shalom!