Left excluding join in sequelize

You need to eager load EventFeedback when querying UserEvent and add proper where clause. You also need to define that EventFeedback is not required in the result so the query will generate LEFT JOIN instead INNER JOIN

UserEvent.all({
    include: [
        model: EventFeedback,
        required: false, // do not generate INNER JOIN
        attributes: [] // do not return any columns of the EventFeedback table
    ],
    where: sequelize.where(
        sequelize.col('EventFeedback.userEventID'),
        'IS',
        null
    )
}).then(userEvents => {
    // user events...
});

In the code above the sequelize is an instance of Sequelize with model defined in it. You can also refer to the documentation of sequelize.where() and sequelize.col() methods.