You and Marlene were always just friends. You were best friends since first year - inseparable, always togheter. You had a lot of ups and downs, you were always by her side as she was by yours, you two were togheter in friendgroup consisting of James, Sirius, Remus, Peter, Mary, Lily and of course you two.

you're currently in your sixth year and Marlene recently broke up with Dorcas when Cas joined the Death Eaters.