Nerwen Im not sure why you think that Luthien did not have a hard life. Sure the first brief years were probably easy for her as a royal Elf Princess of the house of Thingol. But everything after that is simply awful. She lived through the death, ruin and ransack of her fathers house. Watched as her lover really died twice. Watched as her did eventually died and early on as there was no such thing as the Half Elven at this stage thought she would never see him again. She fought the most awful of any of the Dark Forces ever to walk Arda. Left the country of her birth to live on a tiny Island. Returned from the dead to break her Mothers heart, and finally died probably wearing a cursed Silmaril. Sounds pretty awful to me....
Same would apply then for Galadriel for example, she lived through the death, ruin and ransack of her fathers and uncles house too, saw all her relatives die, that was nothing extraordinary this times.
Furthermore every women would have done what Luthien did for the men she truely loved, if she would be successful is another matter. That was self-serving and kinda selfish, she did it for her own desire (Beren) and not for the community. She accepted that her parents would life in grief forever.
Left the country of her birth to live on a tiny Island
But that´s exactly what she wanted to, so I don´t expect her to be too unhappy about that. She was able to return with Beren, have a family with him and be with him forever after dead.
In this respect Galadriel is more selfless, she accepted that her last home on earth would vanish by destroying the ring, knowing or thinking that she was not able to return to Valinor, so she would no longer be protected from the affects of time. Other than Luthien she chose to life in ME hell over a peaceful life in aman to fight evil or for the exercise of her talents, whereas Luthien only became active after Beren entered her life, did she before that event cared about what was going on in ME? I don´t got the impression. Galadriel did more for the greater good than Luthien IMHO. Luthien is IMHO a flat character, I see more character in Galadriel. Luthien is like the little beautiful princess which does everything to save her beloved, Galadriel on the other hand gives me the sense of true strenght, intellect, and the will to have some impact on the development of the world. If Beren wouldn´t have come, Luthien maybe would sit these days in Doriath still (or in Aman). Luthiens life turns about love, that´s kinda boring, even if her deeds are not.
I know Tolkien said that Luthien was the greatest elf, but did he maybe change his mind? Becouse in the Lotr appendics he said hat galadriel was the greatest of elven women, either that´s because Luthien left the circles of the world or he really did change his mind, for I take his statement more for general and not tied to some timeframe, except he says so of course. But then there is the quote from "Morgoths Ring" I believe where Luthien is said to be the greatest together with the greatest elves of Valinor (Feanor and Galadriel), alas I don´t know which statement was his last.
To return to the topic, Galadriel had at least a life as hard as Luthiens IMHO and maybe a broken heart too, but I don´t think too much, cause in her wisdom she would surely see that all this is Erus plan and that it has to be.