I mean, for the purposes of the general gist of the feeling here, it doesn't really matter either way.
That is to say—What exactly he felt about his sister could be construed either way (he's obviously unusually shaken up about her getting married, but that could be for any number of reasons; she might be moving far away to live with her new husband, for instance), but either way the main point is he's grown up emotionally dependent on her, and can't be anymore.