There are hints about Julia's ex and the boss' grandson, so I guess there are 2 antagonists. Unless I missed something or can't remember now.
At the end, if we are not in Julia's path, her ex leaving prison cutscene doesn't play, so I think he will not be on our way if we are not dating her
At the end, if we are not in Julia's path, her ex leaving prison cutscene doesn't play, so I think he will not be on our way if we are not dating her