[RMDupree]

I guess the answer to the Arwen question would be the obvious one.

She didn't know they (Legolas and Gimli) were leaving for the Havens and they didn't know where to find her (Arwen).

[Bear_in_RoseBear]

It's possible that's the case... also, it may be that they took off while Arwen was still busy ordering things after Aragorn's passing; that is, they may not have stuck around. (hmm)

By the way, the stuff about Aragorn and Arwen is in Appendix A to ROTK, section (v): "Here Follows a Part of the Tale of Aragorn and Arwen". It includes their first meeting and their parting.