There are 2 different assignments for the cuddle lounge - Servants and Prisoners.
Servants are the top 20 boxes on the Collection tab. You can promote Guests or Prisoners that have a positive opinion with you to be a Servant.
When looking at the Cuddle Lounge in the Facilities tab, there will be two values - Servant Cuddle Points and Prisoner Cuddle Points. The number in parenthesis will say +X opinion/cycle. A cycle is a floor/level of the dungeon. So, gains happen whenever you finish a floor.
Servant Cuddle Points is how much opinion your Servants will gain.
Prisoner Cuddle Points is how much opinion your Prisoners will gain. You can maximize this number by having high-ranking, dominant servants. Rank is in the top left corner of character portraits. Dominance is mostly just trial and error testing all your options.
Depending on the Servants you have available to you, the gains might be rather small at first.