faves.php

<?php

// on favorite
add_user_meta( get_current_user_id(), 'tca_favorites', get_the_ID() );

// retrieve
$faves = get_user_meta( get_current_user_id(), 'tca_favorites', false );

$faves = array_unique( $faves );

foreach ( $faves as $favorite_id )
{
	$favorite = get_post( $favorite_id );
}