It could be due to her being influenced by the cultural or social environment she is in. If such stories are prevalent in her social circle or the media she consumes, she might unconsciously become obsessed with them. Another aspect could be her own curiosity about nature or biology in a rather strange or unorthodox way, where the 'big cock' aspect is just a part of a larger exploration of the natural world, although this is a less common reason.
Well, it could be that she has a strange sense of curiosity. Maybe she's lacking excitement in her own life and this strange story about the neighbor has caught her attention in an extreme way.
There were many reasons for a novel's fascination. The most common one was that the novel's plot was fascinating. The story was full of thrills, suspense, romance, warmth, and other elements that could attract the reader's interest. The characters in the novel had distinct personalities and unique characteristics. Through reading the novel, readers could understand and feel the inner world and emotional changes of the characters. This was also one of the important reasons for attracting readers. The novel's worldview and setting could also stimulate the reader's interest and make the reader have the desire to explore the unknown world. Finally, the novel's language was rich and colorful, allowing the readers to enjoy the beauty and pleasure of the language in the process of reading.
She dates him perhaps due to some aspect of their sexual relationship or attraction. But this is a very general and more acceptable way compared to the original statement.