The 21-year-old Wigan midfielder revealed on Monday that he had asked not to be selected for this summer's tournament because his father is undergoing cancer treatment.
Ireland boss Giovanni Trapattoni said: "Last week, he called me and told me what had happened with his family, and I told him, 'I am sorry, I am very, very sorry'.
"But he has decided to remain at home because he has a very heavy duty for his parents.
"I told him immediately that we would continue to follow him and that he will be in our plans for the future. He said, 'Thanks for this'."