Apparently, in order for her to breed, she has to use the same method as the species she inhabits. That means that, in this case, she needs human semen. That was why she had no choice but to reveal who she was to me and choose me as her mate. (Though it seems she would have been fine with anyone who could keep the secret.)

She threatened to eat me if I refused. But now, I'm satisfied. In her transformed state, she always adapts the depths of her throat to the best shape to squeeze out my semen, and because of that, I can't stop ejaculating. Eventually, I began to fear this sensation.

At this time, I had no idea that the many young parasites born from my semen would eventually infest most of the girls at school, and I would become forced to forever be a source of semen for the aliens.