I had two experiences with Reputation, my heartbreaker and another. The heartbreaker had no problem at all getting her boyfriends. Like I said before, I just made her friends with all of them before hand, that way i only took a few interactions to become romantic interest. I was sure to end the dates by saying goodbye, then went back to them to break up. After three breakups she got the Reputation of 'Exploring their Options', but never was accused of cheating and none of the new victims ever acting strangely.
The other experience I had was one of my Sims autonomously kissed his sister-in-law while his wife was at work. I realized it because it came up that he was 'Naughty'. The wife came home, went about her business and never got mad, but the next Sim morning I had him perform 'ask to just be friends'. Since then the Naughty was removed and he hasn't had an issue with either of the two sisters.