This site names this specific bonus guide directly as Bonus 4: the Preliminaries Guide.
This site describes it directly as ideas for making moments together more memorable — worth reading it as the third and final relationship-themed guide among the five, alongside Intimacy and Connection.
This site is direct that these are educational digital guides it names and describes at a high level — worth checking the guide's actual content yourself once received, rather than relying solely on this brief description.