A Custom Meta Boxes 2 plugin addition that will take care of saving non serialized meta for repeatable fields and groups
Thes meta splitting will only apply to posts (of any type, not just post and page) and users. It will not apply to option pages.
Download, copy and paste into WordPress plugin folder and activate; this plugin has no UI.
The plugin exposes no template tags or functions and will simply save non serialized meta in the database.
The code below will add a repeatable text field to the page, id my_text, and a group field with the id of my_group; any entry in the repeatable text field will be saved to the my_text_split meta while entries in the group field will be saved in the my_group_title and my_group_description meta.
add_action( 'cmb2_init', 'yourprefix_register_repeatable_group_field_metabox' );
/**
 * Hook in and add a metabox to demonstrate repeatable grouped fields
 */
function yourprefix_register_repeatable_group_field_metabox() {
	/**
	 * Repeatable Field Groups
	 */
	$cmb_group = new_cmb2_box( array(
		'id'           => 'metabox',
		'title'        => __( 'Repeating Field Group', 'cmb2' ),
		'object_types' => array( 'page', ),
	) );
	$cmb_group->add_field( array(
		'name'       => __( 'Repeatable text', 'cmb2' ),
		'desc'       => __( 'field description (optional)', 'cmb2' ),
		'id'         => 'my_text',
		'type'       => 'text_small',
		'repeatable' => true,
		'on_front'   => false,
	) );
	$group_field_id = $cmb_group->add_field( array(
		'id'          => 'my_group',
		'type'        => 'group',
		'description' => __( 'Generates reusable form entries', 'cmb2' ),
		'options'     => array(
			'group_title'   => __( 'Entry {#}', 'cmb2' ),
			'add_button'    => __( 'Add Another Entry', 'cmb2' ),
			'remove_button' => __( 'Remove Entry', 'cmb2' ),
			'sortable'      => true
		),
	) );
	$cmb_group->add_group_field( $group_field_id, array(
		'name' => __( 'Entry Title', 'cmb2' ),
		'id'   => 'title',
		'type' => 'text',
	) );
	$cmb_group->add_group_field( $group_field_id, array(
		'name'        => __( 'Description', 'cmb2' ),
		'description' => __( 'Write a short description for this entry', 'cmb2' ),
		'id'          => 'description',
		'type'        => 'textarea_small',
	) );
}
The _split postfix might not be ideal for any application so the plugin comes with the cmb2_meta_split_postfix filter to allow for the customization of that.
By defaul the meta splitting will apply to any repeatable or group field but that might not be the desired outcome; the solution if two-fold: either apply a filter to the cmb2_meta_split_applies filter (return false to prevent the splitting from happening) or set the nosplit parameter on a field.