[Mithadan]

In Morgoth's Ring, a great deal of information is provided about elvish marriages in general and Finwe's marriage to Miriel. After Miriel abandoned her body and entered Mandos and it became clear she would not return, Finwe petitioned the Valar for permission to seek a new wife. Elvish tradition allowed and elf to marry only once. Death would not sunder a relationship because the deceased would eventually return. The Valar decided that if Miriel chose to not return from Mandos, Finwe could remarry and he did. After he was slain, he elected to remain in Mandos in grief and sorrow for his people (and perhaps to share Feanor's fate). Miriel was thus allowed to exit Mandos, the result being that Finwe can never return. Morgoth's Ring contains a great deal of philosophy and discussion of Elvish customs beyond the thumbnail of the story I have provided.