There isn’t a widely established term for this exact idea. Strictly speaking, it isn’t a portrait if no person appears in the frame.

The closest standard category is usually still life if the image centers on objects arranged or presented as the subject. If the scene is more about showing a room, it could lean toward interior/real-estate photography; if it is meant to tell a story about someone’s absence or life, it may overlap with photojournalistic or narrative imagery.

For an assignment, a clear description would be something like “still life suggesting human presence” or “environmental still life.” Informal phrases such as “empty place” or “implied portrait” may also communicate the idea, but they are not standard technical genres.

So: use still life as the safest established term, then explain that the objects and space are intended to imply the absent person.