I was reading this from metafandom.
Interestingly enough, neither the novels nor the films offer any possibilities for female readers/filmgoers to identify with strong, active or sexual women
There’s Arwen, the ethereal half-elven bride of Strider/Aragorn, whom in the films gets her one moment of glory in Fellowship, where she rides like the wind, bearing an injured Frodo, while being chased by nine Ringwraiths (there were quite a few male readers of the LotR trilogy who were upset at the liberties that director Peter Jackson took by making Arwen a pseudo-heroine).
However, much of the trilogy Arwen is a more passive character.In the films she spent more time pining for her lover, waiting for Aragorn to save the world and claim her. The kissing scenes (loves scenes – heaven forbid!)between her and Aragorn were incredibly tame and one got the feeling that Arwen had no sex life until Aragorn.
So, if Arwen is passive, she's bashed for being boring, but when they change her role to be more active, she's bashed for being a Mary Sue.
The poor girl just can't win, can she?