yeah, i looked through the guide and i thought Eira would want an MC that's compassionate, wants to listen, blunt, and whatever else seemed to "fit" her personality, but it ended up on vincent's route so i tried the opposite and it ended up on his route again (there's nothing unlocked in the memories for her). That's when i started writing down the choices, then i just started randomly choosing different options and it always ended up with vincent.