@Shaheena_Sheikh
ID must be unique, if you have text field with id(granite:id) in side multifield, there will be multiple elements with same id. You will always get the first element.
So use class(granite:class) instead and get the last element(selector text-field-class:last) of that class when new item is added.
Example:
Add class(granite:class) to id text field (here I am using id-text-field). Try below code to get each text field value inside multifield.
$(".coral3-Multifield-item").each(function( index ) {
console.log($(this).find(".id-text-field").val());
});