If statement is not working for some inputs

I am trying to make a password checker in C#, and when I enter smaller values for the username and password, the program executes as expected, but when I enter larger values, the program doesn't do anything. The if statements are not validating for larger inputs. Here is my code:

Console.Write("Set a username: ");
        string username = Console.ReadLine();
        Console.Write("Set a password: ");
        string password = Console.ReadLine();

        Console.WriteLine("Are you sure that you want these as your username and password? (Y/N)");
        Console.Write("Enter here: ");
        string decision = Console.ReadLine();

        if (decision == "Y" || decision == "y")
        {

            Console.Write("Enter your username: ");
            string inputUser = Console.ReadLine();
            Console.Write("Enter your password: ");
            string inputPass = Console.ReadLine();

            if (inputUser == username && inputPass == password)
            {

                Console.WriteLine("Username and password match correctly! Restart the program to try again.");

            }
            else if (inputUser == username && inputPass != password || inputUser != username && inputPass == password)
            {
                int i = 0;
                while (inputUser == username && inputPass != password || inputUser != username && inputPass == password && i < 2)
                {

                    Console.WriteLine("Username or password don't match correctly. Please try again.");
                    Console.Write("Enter your username: ");
                    inputUser = Console.ReadLine();
                    Console.Write("Enter your password: ");
                    inputPass = Console.ReadLine();

                    i++;


                    if (inputUser == username && inputPass == password)
                    {
                        Console.WriteLine("Username and password match correctly! Restart the program to try again.");
                        break;
                    }

                    if (i >= 2)
                    {

                        Console.WriteLine("Too many attempts. Please restart program to try again.");
                        break;

                    }

                }
            }

There are no error messages from visual studio, so I'm not sure what to do.