groups_is_user_pending( int $user_id, int $group_id )

function groups_is_user_pending( $user_id, $group_id ) {
	$is_pending = false;

	$user_groups = bp_get_user_groups( $user_id, array(
		'invite_sent' => false,
		'is_confirmed' => false,
	) );

	if ( isset( $user_groups[ $group_id ] ) ) {
		$is_pending = $user_groups[ $group_id ]->id;
	}

	return $is_pending;
}