Well the entire premise is flawed. Ayumi is the only choice, whether the choice gets made or not, or whether the choice gets picked by MC or not. And either way no matter what the choice and by whom it gets made, Ayumi either dies by the power leaving her, or dies by the power killing her. Since her end is guaranteed, MC has to be with or pick her until his, their or her end; otherwise their entire motivations, backstory and character are negated. As it stands, until new information arrives (read: deus ex machina) the endgame can only be shit and destruction.
Also third choice isn't a choice since whatever set of options happens are entirely in human organizations hands. And they'll happen whether MC picks or not.