How to get working logging with flask-login?

I'm developing an app in Python that includes logging users. I'm using flask incl. SQLAlchemy, flask-login and flask forms. These are my codes for registering and logging (in module routes.py):

@app.route('/register', methods=['GET', 'POST'])
def register():
    register_form = RegistrationForm(request.form)
    if request.method == 'POST':
        if register_form.validate():
            email = request.form.get('email')
            password = request.form.get('password')
            username = request.form.get('username')
            existing_user = User.query.filter_by(email=email).first()
            if existing_user is None:
                user = User(username=username, email=email,
                            password=bcrypt.generate_password_hash(password))
                db.session.add(user)
                db.session.commit()
                login_user(user)
                return redirect(url_for('home'))
            flash('A user already exists with that email address.')
            return redirect(url_for('register'))
    return render_template('/register.html',
                           title='Create an Account',
                           form=RegistrationForm())


@app.route('/login', methods=['GET', 'POST'])
def login():
    login_form = LoginForm(request.form)
    if request.method == 'POST':
        if login_form.validate():
            email = request.form.get('email')
            password = request.form.get('password')
            user = User.query.filter_by(email=email).first()
            if user:
                if user.check_password(password=password):
                    login_user(user)
                    next = request.args.get('next')
                    return redirect(next or url_for('home'))
        flash('Invalid username/password combination')
        return redirect(url_for('login'))
    return render_template('login.html',
                           form=LoginForm())

As can be seen, they are written in a similar manner. This is my logger function (in module models.py):

@login_manager.user_loader
def load_user(user_id):
    return User.query.get(int(user_id))

Registering works as expected, but the same can't be said for logging in. When I use valid email and password (saving in sql works fine), my web app always flashes 'Invalid username/password combination'.

Can anyone help?

I found a solution. My form for Login looked as follows:

class LoginForm(FlaskForm):
    email = StringField('Email',
                        validators=[DataRequired(), Email()])
    password = PasswordField('Password',
                             validators=[DataRequired()])
    confirm_password = PasswordField(' Confirm Password',
                                     validators=[DataRequired(), EqualTo('password')])
    remember = BooleanField('Remember Me')
    submit = SubmitField('Log In')

I copied my Register form and forgot to delete confirm_password field. It is not being confirmed while logging in, so the field conditions is not satisfied --> form.validate_on_submit is false.