No it doesn't seem like that. It's more likely that he know that knight was her ex and if gonna become saintes she gonna remember her feelings for knight.
Honestly, I feel like it could be true. He kept on mentioning about the story changing, and he's afraid that the story will go back to its original flow. It's quite sad, and I really know where he is coming from and why he acts that way. Although I do hope Maise finds out about the truth, their relationship might not be the same anymore. Like, the relationship is pretty toxic and we already have Maise doubting the guy.
wait so yse knows about the original story?????? broooo... (⊙…⊙ )