In Holes, why did Elya tell Myra to choose Igor?

Elya told Myra to choose Igor because she did not really love him, and she proved self-centered.

In the past, there is the story of Elya Yelnats and Myra Menke.  Elya is in love with Myra.  So is Igor Barkov, the pig farmer.  He is fifty-seven years old though, and you would not think that he was the most attractive of mates for a teenager.  Myra's father wants to know what each of them can offer.

"I will trade you my fattest pig for your daughter," Igor offered.

"And what have you got?" Myra's father asked Elya.

"A heart full of love," said Elya.

"I'd rather have a fat pig," said Myra's father. (Ch. 7)

Myra does not choose right away.  This in itself proves that Myra does not really love Elya.  If she did, she would have chosen him and not worried about the pig.  She is selfish and does not love either man.

Madame Zeroni tells Elya not to bother with Myra, because just because she is pretty does not make her a good wife.

"I'm in love with Myra Menke," Elya confessed. "But Igor Barkov has offered to trade his fattest pig for her. I can't compete with that."

"Good," said Madame Zeroni. "You're too young to get married. You've got your whole life ahead of you."

"But I love Myra."

"Myra's head is as empty as a flowerpot." (Ch. 7)

Madame Zeroni gives Elya a piglet, and tells him to take it up a mountain and sing to it.  As he does this, the piglet will get bigger and he will get stronger.  Then he is supposed to carry her up the mountain.  She warns him that if he doesn’t he will be cursed. 

Elya carries the pig, and it gets bigger.  When Myra’s father is presented the two pigs, they weigh the same.  Myra cannot decide which man to marry.  She tells the men to choose a number.  This finally convinces Elya that Madame Zeroni was right.  He tells her to marry Igor, and gives her the pig as a wedding present.  He goes to America, without fulfilling his promise to Madame Zeroni.  He is sad because the girl he loves does not love him back.