Star Trek: The Next Generation (1987): The Next Phase

Stardate: 45892.4. While the Enterprise helps a Romulan science vessel, an accident occurs which forces Geordi LaForge and Ro Laren slightly out of 'phase', causing them to become undetectable to everyone but each other. As a result, the crew thinks they are dead and make arrangements for their funerals, even though they are closer than the crew realise.