They were losing the war. At this point it was not another of Harry’s pessimistic claims but a tried and true fact. After Dumbledore was killed by Voldemort at the Department of Mysteries and Snape revealed his true allegiance to the Dark it started to go downhill. The Order lost its leader and its spy in one fell swoop and it had them spinning. It hadn’t been safe enough to return to Hogwarts for their second year. Despite Molly’s pleading they were low on able fighters and there really wasn’t any option left but to let everyone who was will fight. One by one they were picked off. The first was Ginny, in the madness following her death the twins were angry enough for retribution and only ended up getting themselves killed too. Next was Remus, the last tie to his family Harry had left, his surrogate godfather in the wake of Sirius’s death. It very dearly broke Harry, but he refused to let himself grieve until the fight was over, or he himself died. There were no other options. Despite their desperation it wasn’t until Ron joined his sister and the twins in an explosion that took out nearly half the remaining order that he and Hermione came to a decision. They knew that messing with time was messy business, but at this point, even if they wiped out their own existence they would be taking Voldemort and his army of monsters with them.