If Lona voluntarily enters into sexual contact with monsters in slavery, it pumps up her reputation, would allow her to buy food, clothes, and things necessary for escape. When escaping from slavery, the reputation would be reset.

So your suggestion is, add a new reputation meter for monsters?

If Lona had sex with monsters often, the monsters will agree to trade with her, or even agree to give her free stuff?

Yes. but pumping should be long. (This is needed if the player is unable to escape from slavery.)

must be dropped when escaping.

Sounds like an anime material, called "Daily Life of a Orkinds' cave as a Sex Slave"

Where in the end, with all the hardships and almost getting killed in the process, Lona leaves the cave successfully with max Orkind reputation.

reads like degrees of lewidty mechanices do not like

just tired of being fucked for 25 levels. Although in the end he pumped out stealth and got out.