Canonical mode in Assassin's Creed Shadows was introduced at the request of fans and will not affect the romantic lines in the game

Assassin's Creed Shadows, which is coming out on 20 March 2025, is preparing several innovations for the series, including a new canonical mode. This mode will allow players to choose between a linear story and a more interactive narrative.
Here's What We Know
Canonical mode is the first of its kind in the franchise, offering players the ability to disable the selection of key moments in the story and enjoy a linear narrative. According to Creative Director Jonathan Dumont, this mode was created based on feedback from fans who wanted to be able to choose between interactive storytelling and a traditional linear story.
"We realised that some fans wanted to be able to choose between interactive storytelling and a traditional linear story," said Dumont. "So we added a mode that makes the story more canonical and linear."
This mode will be available from the very beginning of the game and cannot be changed during the game.
The game will also lack the canonical romance lines, allowing players to choose their own romantic stories for Naoe and Yasuke. According to Brooke Davis, associate director of storytelling, the lack of canon romances allows players to decide for themselves who they want to choose.
Source: GameRant