Themes
Death cannot stop true love. All it can do is delay it for a while.
— Westley ‧ The Princess Bride

Behind the line May contain spoilers.
Our reading
An editorial interpretation.
The promise treats death as a delay in love rather than its ending. That turns the strongest imaginable separation into something temporary, giving the words their romantic confidence. 'For a while' makes an immense obstacle sound almost small beside the love being claimed.
Context reviewed