So shes doomed in every timeline, and hes trying his hardest to save her. Guessing the reason shes added to the party, is hes already tried not bringing her into danger, and she still got herself killed on her own so he needs her by his side to ensure shes safe. Likewise, the "speedrun" part is likely due to another event in her doom; possibly a family member ill in the opposite direction forcing her to leave the party (and dying out there), that he needs to conclude his adventure before that happens to escort and save her.
