There are absolutely irreparable consequences to your actions in this game. You have to "plan ahead" in the sense that you have to be sure what path you want to go down because other paths will become closed or non-existent. It also is sometimes not obvious which path makes the most sense to take, which is by design.
Without trying to spoil anything, I made a mistake with one of my characters which caused them to permanently leave the group and I can't get them back.