getline() not reading all lines in txt file

[beeb]

So I made this function to check username and password. I've put two usernames and two password in each file. I tried to use a loop to read all lines but it's not working. I'm only able to log in with just user1 account. pw & username text file is setup like this

user1
admin

void auth( string user, string pass )
{
     string inpass, inuser;
     ifstream passfile;
     ifstream userfile;
     passfile.open ("password.txt");
     userfile.open ("username.txt");
     if (userfile.is_open() && passfile.is_open() )
     {
        while(getline(passfile, inpass))
        {
           while(getline(userfile, inuser))
           {
              userfile.close();
              passfile.close();
              do {
                    if(user==inuser && pass==inpass)
                    {
                        system("cls"); //command line function to clear the screen
                        cout << "Welcome " << user;
                        break;
                    }
                    else
                    {
                        cin.clear();
                        cout << "Username or password is incorrect. Please try again." << endl;
                        cout << "Please enter your username: ";
                        cin >> user;
                        cout << "Please enter your password: ";
                        cin >> pass;
                    }
                 }while (true);
           }
        }              
     }
        else cout << "Unable to open file";
}