personally I’ve never liked the headcanon that hobbit society as commonly practicing (or at least openly accepting of) polyamory when discussing rosie/sam/frodo. hobbit society is modeled after late 1800’s England. im no expert but I can’t imagine it was totally conventional and accepted then when it isn’t even now.
Like, why does it have to be a common and accepted practice, why can’t Rosie herself be unusual and willing to live an unconventional life in an unconventional relationship? fully support Sam being a bicon and setting up home with two gorgeous babes but I just feel it adds so much more complexity to Rosie’s character to start out as as a normal hobbit with a normal hobbit society’s mindset.
She marries sam who started out as normal as she did but is now changed irrevocably, she understands that Sam and Frodo are going to be linked forever by shared experiences she can’t relate to and that a huge part Sam’s heart will always belong to him. but she does love Sam more than the social conventions she’s seen all her life
and maybe she might have some complicated feelings about things at first, but she eventually grows to love them both deeply and they form a unique bond and yeah she never can understand the scars they brought back from Mordor but she brings her own qualities to the relationship that are loving and supportive and valuable, and this becomes really important to Sam for the rest of their lives because he doesn’t have to be alone in missing and mourning Frodo after he leaves for the undying lands
Yeah it’s not as nice and easy as the “society is totally accepting and has the progressive moral standards and values that we have now” but imho it gives an underdeveloped female character so much more richness and dimension than “rosie was totally down to share Sam with Frodo because it was totally fine and normal”