 She later dumps Martin, who loved her but she was not sure she felt the same.Another reason (which is not very clearly shown) might be that she thought Simon was returning—whereas he only came for vacations—and they might get back together (because it would no longer be a long-distance relationship).When Simon comes home (at the end of season eight), it was vaguely revealed that their relationship did not work out, because over the summer Cecilia went away to college, and it was only when Simon begins dating and having sex with Georgia (in season nine) that it is revealed that they had broken up.