This sort of thing might sound alluring, but the people involved would definitely not feel that way.
The sadistic nature of harpies, who loved to inflict pain, would not engage in tender talks of love with these males. Instead, they used their charm songs to forcefully mate, and the process was bloody. In their excitement, they would tear apart their partners with their four talons as much as possible.
Even if someone could survive mating with the first harpy, there were still the second, third, and even fourth waiting for him, draining every last drop of his energy and blood until he was completely dry before they feasted on him—literally.
In his past life, Gaven had witnessed a man revived by the Complete Resurrection Spell after being captured by harpies. Although he hadn't gone mad, he was not far from it. A burly barbarian, at the slightest hint of a sweet female voice, would curl up in a ball, shaking like a sieve.
Gaven, still some distance away, was also affected.