I'm a little worried about the possibility that Marino did appear, and that Schnee may have done something to her in the hopes that if/when Shin reappeared, she'd have him all to herself.
...I've probably just been reading too many yandere stories.
If that did happen, though, hopefully Schnee just convinced her to move on and find someone else, while also keeping her existence a secret from others like the Gold Company. I'd hate for this story to get detailed by a main character going full-yandere.