I don't want romantic interactions from other sims(npc) while my sims are in a relationship.

[Adden-]

I don't know what configuration I'll have or what it will be, but the npc flirts with a couple in my family and they don't reject flirting from the npc, causing the relationship I made to not be respected, sometimes they agree to have sex with any npc.
Is there a setting or something that can help me?
practically my sims don't respect the relationship accepting flirtation from other sims

and sorry for my bad english

[LittleRedSonja]

1 hour ago, Adden- said:

I don't know what configuration I'll have or what it will be, but the npc flirts with a couple in my family and they don't reject flirting from the npc, causing the relationship I made to not be respected, sometimes they agree to have sex with any npc.
Is there a setting or something that can help me?
practically my sims don't respect the relationship accepting flirtation from other sims

and sorry for my bad english

Give both of them the "eternally faithful", you can do it the same way you give other "wicked" traits: Click on the sim, then "wicked" then "personalization" then "give wicked traits", and there you choose "Eternally faithful".