I would like to introduce the concept of degrading abilities. The idea is that some abilities increase when the player uses certain items, but decrease with lack of use. It's kind of like how skills decrease when a character is in jail in Skyrim.
Strength: For example, strength increases when wearing heavy armor or swinging a weapon. The heavier the weapon, the stronger the player becomes. Additionally, a player's strength increases faster when they consume protein-rich foods.
Intelligence: How should intelligence be handled? Reading books should increase intelligence. How quickly should it degrade, if at all? Should players reread the same books to maintain their intelligence?
Taking an idea from SexLab Aroused, overly aroused characters' skills would increase more slowly.
I'd say a character with a sex addiction should lose intelligence. I'd imagine that satisfying their arousal and constantly pursuing sex would cause this.