She could be rationalizing it away "while this person looks similar, the actual person is so busy. There's no way they could be one and the same"
Or because she has preconceptions about him, there's no way someone nice could've been him. Etc etc.
People do it IRL. It's not hard to think that someone fictional could :)
there is also how she is somehow not recognizing the emperor's voice when she is with Ran. She got chills in the past when hearing his voice, and even without seeing him, she knew who he was. How could she not recognize it when it's just slapped on some dude that has the same exact features as the emperor and not make that connection??? (￣∇￣")
is Marie is so fvckin blind to not notice the difference of the Prince and the guy "Ran" gosh...His hair and eye colour clearly can be noticed by anyone...