can you name 3 instances of men marrying elves in Tolkien's lore?

Answer 1

Beren & Luthien
Idril & Tuor
Aragorn & Arwen


Half-elven
In J. R. R. Tolkien's fictional universe of Middle-earth, the Half-elven (Sindarin singular Peredhel, plural Peredhil), are the children of the union of Elves and Men.

History

The First Age

Two important marriages in the First Age of Middle-earth resulted in the mixing of Elvish and mortal blood.

The first of these was between the mortal Beren of the House of Bëor and Lúthien, daughter of the Elf Thingol, king of the Sindar and the Maia Melian. Beren died in the quest for the Silmaril, and in despair, Lúthien's spirit departed her body and made its way to the halls of Mandos. Mandos allowed them a unique fate, and they were re-bodied as mortals in Middle-earth, where they dwelt until their deaths.

Their son Dior was thus one-quarter Elvish by blood, one-quarter Maian (thus half-immortal) and half-human (thus half-mortal), and although since he was born after their re-embodiment, the nature of his mortality is quite unclear. He died young in any case, when the sons of Fëanor attacked Doriath.

Dior's wife was Nimloth, a Sindarin Elf, and with her he had three children: Elwing, Eluréd, and Elurín. Eluréd and Elurin were slain along with Dior---or escaped, never to be heard of again, as legend goes---while Elwing escaped to the Mouths of Sirion.

The second marriage of Men and Elves in the First Age was between Tuor of the House of Hador and Idril of the Ñoldor and Vanyar. Their son was Eärendil. After the fall of Gondolin, Eärendil also escaped to the Mouths of Sirion, and married Elwing. They had two sons, Elrond and Elros.

Post-War of Wrath

After the conclusion of the War of Wrath, Manwë determined that the surviving half-elven would have their choice of fates: to be counted as Elves, and granted eternal life in the Undying Lands; or to be counted as mortals, and granted the ineffable Gift of Men. This choice could be delayed, although not indefinitely.

Eärendil would rather have chosen the kindred of Men, but he chose the Elves for his wife Elwing's sake, who chose the Elves. Eärendil would thereafter forever sail the heavens in his ship Vingilot, the Silmaril of Beren and Lúthien on the prow. In Middle-earth, he was seen as the evening star, and the light of his Silmaril was captured in the Phial of Galadriel. Elwing built a tower in the Shadowy Seas and often met him on his return.

Elros chose to be counted among mortals, and became Tar-Minyatur, the first king of Númenor. He finally took his death (for those kings were able to choose when they died) at the age of five hundred years. The heirs of Elros were not given this choice, but their lifespan was enhanced many times that of normal Men, and they had the freedom to take it when they willed. In later times the Númenórean kings, descendants of Elros, regretted their forefather's choice, and this helped lead to the Downfall of Númenor.

Elrond chose to be counted among the Elves, serving the household of Gil-galad until the end of the Second Age, and founding Rivendell in the Third. He married the Elf Celebrian, daughter of Celeborn and Galadriel, and sailed into the West at the conclusion of the War of the Ring.

The children of Elrond and Celebrian were also given free choice of kindred, and therefore Arwen could choose to be counted amongst the Edain even though her father had chosen to be counted as Elven. She exercised this option, marrying Aragorn II Elessar, king of the Reunited Kingdom, and finally dying at the age of 2,901 years. Their son Eldarion and their daughters were not counted as Half-elven, but rather as Dúnedain restored.

We are not sure of whether Elladan and Elrohir chose to be of the Edain or the Eldar; this information is not given in the books. However, since their choice was expressed by whether they would follow their father to Valinor at the time of his own departure, and they were described as remaining in Rivendell, some readers assume that they chose to be of the Edain.