Narrative Connection
How these two moments in the story relate
Why These Connect
The narrative assertion
"Astra's betrayal in Episode 25 (luring Romana) directly causes the Doctor to lose Romana in the time loop, as he is left alone in the cave."
inferred by llm_cross_episode_arc
Why This Matters Across Episodes
The longer arc this connection carries
Astra's actions in Episode 25 (facilitated by the Shadow's control) create the immediate circumstances of Romana's disappearance in Episode 25, driving the Doctor's isolation and subsequent confrontation with the Shadow.
About Causal Connections
A directly causes B. The first event sets forces in motion that produce the second. These are the load-bearing connections of plot--remove one and the story structure collapses.