There is a strong level of flirting going on here. The lady has positioned herself between the guy’s legs. She has one leg wrapped around him in a very sexual pose. Their hips are close together, indicating interest. She has tipped her head back to display herself to her best advantage. Showing off her neck is a very subconscious gesture of sexual attraction, "Come here and kiss my neck". Women only draw attention to their necks when they are sexually interested.