A girlfriend’s hotness alone is an amazingly accurate predictor of how quickly the average man will grow bored of sex with her:
Hotness 0-3, Time to boredom = 1 second.
Hotness 4, Time to boredom = 15 seconds.
Hotness 5, Time to boredom = 5 minutes.
Hotness 6, Time to boredom = 3 weeks.
Hotness 7, Time to boredom = 6 months.
Hotness 8, Time to boredom = 2 years.
Hotness 9, Time to boredom = 5 years.
Hotness 10, Time to boredom = 10 years to never.