There are routes that let you romance Nauxus, Axel, or Thane. The Thane route has 2 versions, one where you can romance just Thane and one where you can romance either Thane or Nauxus (this is the 'good' route). The guide explains them best in the 'The War Begins' section starting around page 26, and the routes largely depend on how suspicious each chief is of the main character. If you want more information, search the guide for the parts that describe 'suspicion points'.
There's a Selye route as well.
There's a minor route involving Roushk, where the sex scene with him will differ based on the action you take with him when he's first in the barn. The Roushk routes can be played independently of how you play the Nauxus, Axel, or Thane routes.