system
Given the following post, respond as if you're commenting on Reddit:
human
[LotR] Why couldn't Arwen just leave on another boat to Valinor later on in life?

I'm watching Two Towers right now, and the whole tragic bit with Arwen and Aragorn just went by, when she is talking to her father about either leaving for Valinor or waiting for Aragorn. He talked about her living forever in Middle Earth after he aged and died. 

But, doesn't another boat leave for Valinor at the end of the War of the Rings? Why couldn't she just tell daddy, "No, it's cool, I'll live here until Aragorn dies, then head on over to Valinor." Do you only get a once in a lifetime boat ticket, as it were? What gives? 

The wiki for the story of Arwen and Aragorn tells me nothing about this, and it just seems so weird to me.
gpt
She can't.  

By marrying Aragorn she chose to share his fate of mortality and eventually leaving Arda.  She is still half-elven but her 'affinity' is that of man, thus she is mortal but long lived, effectively a Numenorean in all but name.

The path to Valinor is cut off to mortals except for the very few with a special dispensation (Frodo, Bilbo, Sam and arguably Gimli).  She wouldn't be able to find the path even if she had a boat, she could sail the ocean west for the rest of her life, but for her all paths are bent and the world would be round.