Never dated one I don't think but I've definitely worked with one.

You know how whenever a psychopath gets caught having murdered a bunch of people, and there's always some neighbour who is like "OuWh MuWaY GwAhD, they were always such a upstanding, giving, warm person, I don't believe it! They're lying!", and you look at them think "bitch shut up, how can you know this person for ages and not pick up on their craziness?". Listen, until you've seen that first-hand...

Basically this dude was the nicest, most helpful, polite, we had amazing conversations for a whole year. I never picked up on any red flags from him at all, he did seem pretty confident, but not arrongant, and he was chill as fuck, never said anything that upset me, he really was a great guy as far as I was concerned. I liked him platonically, a lot. Until he left. Then, I found out from a very good friend of mine who worked there what he was like after she hooked up with him. Abusive angry text messages (she showed me them), blowing up her inbox, saying shit like "I'll pimp you out and pass you around all the guys here", disparaging comments about her appearance, coming back into the workplace and dogging her out after he left (we worked in a department store).