The Engagement of Marielle Clarac (Manga) Volume 4 by Haruka Momo

Tragedy strikes on what was supposed to be a romantic winter getaway, devastating Prince Severin and dashing his heart. Intrepid Marielle and self-serious Simeon, however, suspect there’s something beneath the surface of this sad story. They set out to investigate, encountering danger and uncovering surprises the likes of which they never expected to find. When the secrets shrouding House Montagnier are finally brought to light, will it destroy all hope of a royal marriage?