I'm always fearful for female mandrills, as they probably weigh about a third of the males and are basically powerless when it comes to mating.
But the female isn't looking unhappy, I think...And what about littele elphant cows, which are mating with huge bulls like Siam in Paris, Tembo in Hannover or Vauka in Kronberg ? ( all three are dead ) And Siam has mated with his own daughter, as she was only almost 4 Years old....