How to do force a Sim to forget a relationship

[Dirty Railroader]

Is there a command/cheat that will allow you to force a Sim to forgot a relationship with another Sim?

[marstinson]

Yes and no. On the "yes" side, I use the Master Controller mod with the Cheats add-on from nraas.net to do this sort of thing. MC allows me to set either the numeric value of the relationship (-100 to +100), or to set the category (Stranger, Enemy, BFF, or whatever) level of the relationship. On the "no" side of things, I'm not aware of a command that will let you reset a committed romantic relationship (Girl/Boyfriend, Fiance, Spouse), although MC can be used to give a Sim enough LTR points to purchase the Clean Slate lifetime reward if you have the Generations EP installed. This will remove all romantic history and reset any existing romantic relationships and eliminate the chance of picking up a negative romantic reputation around town.

Sims whose relationship has been set to zero (Stranger) remain in the relationship panel. I think you can clear that by saving the Sim to the bin in Edit Town mode (with or without their home lot), starting a new game and importing the saved household.