Is it possible to change a Sim's romantic reputation without the Clean Slate lifetime reward?

[Dominoe1305]

One of my Sims has the Cheater reputation, but she has been faithful in her current relationship for 100+ days. I don't want to use the Clean Slate lifetime reward because I don't want her relationship length to be reset to 0. I put a lot of time and effort into her relationship! If I have her go on dates with her significant other and preform romantic interactions in public will her reputation eventually change?

[KiaraRawks]

I've only had this happen to me once. It's when I was playing a type of legacy family and this was before generations came out. The man was sleeping around with loads of other women from around town and his wife had no clue. Then once I installed generations it took until the couple became elders when all of a sudden the wife accused him of all of this. He apologized over and over but it took a large toll on their relationship to the point where she wouldn't even allow him to share a bed with her. I believe I basically just had to have him start over with her in terms of gaining her trust back. He couldnt interact with her romantically and they had to be like friends for awhile. But after that they were alright again. I never had to use the clean slate reward, so I'm not sure if his reputation was ever changed.

Oh and I found this "All recorded days of your Sim's current relationship will be deleted." <- in terms of using clean slate.