If it looks too good to be true, it probably is. Take your time to get to know someone you’re dating.
On the other hand, how many of us can raise our hands and say that our ex-spouse was someone we thought we knew who then did the unthinkable.
I have no actual proof but from the stories I've read it feels like there's a similar number of people who have split between those who jumped right in and those who waited and waited.
Some people, especially abusers are good at either concealing who they are or controlling the narrative. And yes - some people are really good at believing what they want to believe.
I used to say about my xW that she was very good at being charming and sweet for a short period of time but couldn't sustain it. Although she and OM are no into year 7 so there's that.
Your friend's story is certainly a cautionary tale. Long distance relationships can allow for people to only show their best selves which is one of the several reasons I would never get involved in one. And certainly there are professions, generally I believe ones where people have the training to be an authority such as police, doctors (hi kml!), teachers where they can tend to carry that into the relationship and also where infidelity is more common - or so I understand.
On BD H52, W50 T27, M26 S21, D23 BD-9-Mar-16 D-15-Jan-18 Final-19-Apr-18 I am a storyteller. The story may do you no good. But a story is never for the listener. It is always for the one who tells