How to create multiple types os user with Devise using polymorphism and nested_attr

I am developing an application in Rails, which i use Devise for user authentication. But I need more than one type of user, each user type has different types of data, leaving devise for only authentication. I already had created a post about this, with better explanations of the situation, here , but i could not solve the problem , so sorry for creating another post.

My codes:

user.rb

class User < ActiveRecord::Base
  belongs_to :profileable, :polymorphic => true

  accepts_nested_attributes_for :profileable, :reject_if => lambda { |a| a[:content].blank? }, :allow_destroy => true

  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable
end

patient.rb

class Patient < ActiveRecord::Base
  has_one :user, :as => :profileable

  accepts_nested_attributes_for :user, :reject_if => lambda { |a| a[:content].blank? }, :allow_destroy => true
end

patients_controller.rb

def new
    @patient = Patient.new
    @user = @patient.build_user
end

def create
    @patient = Patient.new(patient_params)
    @user = @patient.build_user(params[:user])
    @user.profileable = @patient

    if @user.save
        @patient.save

        redirect_to @patient
    else
        render 'new'
    end
end

private

def patient_params
    params.require(:patient).permit(:name, user_attributes:[:email, :password, :password_confirmation])
end

_form.html.erb

<%= form_for @patient, :url => patients_path(@patient), :html => {:method => :post} do |f| %>

    <%= f.label :name, "Nome" %><br>
    <%= f.text_field :name, placeholder:"Digite o nome do Paciente", required:"", autofocus: true %>
    <br>

    <%= f.fields_for :user do |u| %>
        <%= u.label :email %><br />
        <%= u.email_field :email %><br/>

        <%= u.label :password %><br/>
        <%= u.password_field :password, autocomplete: "off" %><br/>

        <%= u.label :password_confirmation %><br />
        <%= u.password_field :password_confirmation, autocomplete: "off" %><br/>
    <% end %>

    <%= f.submit "Ok" %>
<% end %>

user migration

  t.integer :profileable_id
  t.string  :profileable_type

  And devise attrs

The idea is creating an user and a patient (or other type of user) at the same time, on the form_for patients. And the error i'm getting is:

The user dont save! When i submit the form, the user dont save and i get a "rollback".

Can someone please help me?