she loved the protagonist but she just gave way for her best friend Sekai, so anything she feels and happens between her and makoto are just temporary for her, that they can't have any future with each other because at the end of the story she will be leaving for paris..
there are no solid endings that focuses on her but certain path and flags in the story involves her directly.. but there's one path that the ending has a post-fin ending for Setsuna, in that path she and makoto did ecchi and in the end she sent a postcard from paris to makoto with her pic. pregnant with makoto's kid...