Those are good points, Regis12. But I suppose it's a matter of perspective. Personally, I never thought of a courtesan's duties as cuckolding the player. Traditionally, a cuckold is someone who is aware his wife is being unfaithful to him, but can't do anything about it; he is powerless, and often isn't allowed to have sex with his own wife.
But in this game, if a woman is a courtesan, it's because the player has instructed her to be one. The player is in control, he asks her to do this, and the woman brings back the money that results from it. Plus, the player can have sex with her afterward if he likes (and if they're in a relationship). So, if anything, I see the player more in the role of a pimp rather than a cuckold.
Also, be aware that if there's a special someone you really don't working as a courtesan, you can always assign them to other duties (even if coaching them is required), and then leave the courtesan work to those followers you're less invested in.
Thanks for playing!