Bruno, I appreciate your analysis. As I always say, character archetypes are tools, not rules. You see a story one way. It’s entirely plausible for me to see the story a different way and that include archetypes.

If Fern’s primary obstacle is moving beyond her attachment to the past… and Beau is the emotional embodiment of the past… then an argument can be made that at the level of narrative function, Beau provides opposition for Fern to move forward with HER life.

But as I say, each person brings their own life experience to any movie they watch or script they read. Besides, ultimately stories exist beyond such types as Protagonist, Nemesis, etc. Helpful for analysis, but never to the point where we perceive them as rules.