Did someone notice any effect of Romantic Reputation?

Some of my sims already build a romantic reputation, but It seems there's no impact on the gameplay. Everything look normal in my eyes.

Like what is the effect of being cheater, naughty, manipulator, faithful, dirtbag, etc?

The negative ones make it harder to romance sims, they are more likely to reject romantic interactions from a cheater. the positive ones faithful and eternally faithful give your sims a permanent positive moodlet and from my own observations make them less likely to accept the romantic interactions of a sim who is not their partner (although that may just be coincidence).

Where do you see/keep track of the romantic reputation?

It's in the scrapbook, under Statisics (the pink one). The game also notifies you when your reputation changes.

If your sim has the rejected moodlet, they are in a funk and their job performance and such can be affected. Or so I have read.

I have an elder with a cheater reputation, and I know his love life should be more troublesome but I can't really say I have noticed any difference. He's still scoring left and right.