From my studies and experience I’d argue the fourth paragraph nails it.
“Another possibility is that there is a biological or evolved mechanism that stimulates arousal in this situation. Specifically, seeing another man (or multiple men) bedding a desirable woman may stimulate sperm competition. […]
Every 2 minutes today we snap as many photos as the whole of humanity took in the 1800s.
Digital cameras are now ubiquitous – it is estimated that 2.5 billion people in the world today have a digital camera. If the average person snaps 150 photos this year that would be a staggering 375 billion photos.