These native people's practical rules to help the tribe's survival are paramount in all sexual decisions. Romance is secondary. A special woman provides assistance at many levels.
A fan fiction story of Nick Scipio's Summer camp Universe. Where for the first time Paul and Gina were permitted to stay and don't have to leave the room when their parents starts their private swing party. The parents made rules that there should be no sexual contact between parents and children. This was the part where what Paul felts as he watched his Mother having sex.
Male-perspective bisexual: Paul finds marrying an older, rich woman complicated, not just in terms of his relationship with his boyfriend, but also because the woman's rich lifestyle depends on keeping her former husband, who fancies Paul as well, satisfied.