i read this on dynasty but forgot to save!! its oneshot where the world is ending so girl a invites girl b to take the train to a (cliff?) so that they can jump into the sea and drown together but as they got there, girl a gets off first and holds out her hand to girl b but she hesitates so girl a calls her coward and leaves her, as the train fills with water girl b has inner dialogue and she regrets telling girl a that she loved her. iirc girl a has black short hair and girl b has white hair