SDL2 Window disappears after a second

Running on: Ubuntu 18.04, SDL2.

So my SDL2 window disappears after a second of appearing in the task bar. From researching online I found out that there is a main loop to be used to get events but nowhere stating that it is necessary. I have to display a Video read from OpenCV on SDL2 window. Here is the code:

main.cpp

int main() {
    cv::Mat frame;
    cv::VideoCapture video(constant::video::PATH);

    Display2d* videoWindow = new Display2d(constant::video::WIDTH, constant::video::HEIGHT, "Video", (int)video.get(cv::CAP_PROP_FRAME_WIDTH), (int)video.get(cv::CAP_PROP_FRAME_HEIGHT));

    if (!video.isOpened()) {
        std::cerr << "Cannot open Video file" << '\n';  
    }

    if (SDL_Init(SDL_INIT_EVERYTHING) != 0) {
        std::cerr << "Cannot Initialize SDL" << '\n';
    }

    while (true) {
        video >> frame;

        if (frame.empty()) break;

        cv::resize(frame, frame, cv::Size(), 0.5, 0.5, cv::INTER_AREA);

        //cv::imshow("Video", frame);

        videoWindow->display(frame);
    }

    video.release();
    videoWindow->clear();

    SDL_Quit();
    return 0;
}

display2d.hpp

Display2d::Display2d(int width, int height, std::string title, int frameWidth, int frameHeight) {
    this->width = width;
    this->height = height;
    this->title = title.c_str();

    this->window = SDL_CreateWindow(this->title, SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, this->width, this->height, SDL_WINDOW_SHOWN);
    this->renderer = SDL_CreateRenderer(this->window, -1, 0);   
    this->texture = SDL_CreateTexture(this->renderer, SDL_PIXELFORMAT_BGR24, SDL_TEXTUREACCESS_STREAMING, frameWidth, frameHeight);
    std::cout << SDL_GetError() << std::endl;

};

void Display2d::display(const cv::Mat & mat) {
    IplImage frame = (IplImage)mat;
    IplImage * img = &frame;

    unsigned char * texture_data = nullptr;
    int texture_pitch = 0;

    SDL_LockTexture(this->texture, NULL, (void **)&texture_data, &texture_pitch);
    memcpy(texture_data, (void *)img->imageData, img->width * img->height * img->nChannels);
    SDL_UnlockTexture(this->texture);

    SDL_RenderClear(this->renderer);
    SDL_RenderCopy(this->renderer, this->texture, NULL, NULL);
    SDL_RenderPresent(this->renderer);
}

void Display2d::clear() {
    SDL_DestroyTexture(this->texture);
    SDL_DestroyRenderer(this->renderer);
    SDL_DestroyWindow(this->window);
}