In my run an orientation changed after doing quests with Barb before a possibility of a date with Ruby.I do beleive you need to change your sexual orientation too, from just male to male + female (bisexual) by going out with Ruby? Atleast it was not possible for me to choose ash until then.
But a possibility of this change depends on a talking with Barb after you've found her passport and a flag "barb_rodos" limits this possibility. But I talk about a version w/o a date with Ruby, coz I used saves from a previous version.