I am beginning to realize "boundaries" are a social norm that everyone understands... except me, or at least that's how it feels.

A male once told me to respect the boundaries in our professional relationship.

I asked him to write them down...

He laughed...

But, I wasn't joking. 
Unless I can see them, I have no fucking clue what boundaries are. 

My life is an open book, I never get offended when people say outlandish things to my face. Why are "mentally fit" people so sensitive about everything?

I ended up mentioning that man's wife in an email (to him). I had met her a couple of times before, and he even told me a few personal things about their relationship during our weekly talks. I didn't comment on her behavior, character, personality, or physical appearance. I merely mentioned her name. The next day he said I crossed a line and he no longer wanted to speak with me. 

I am having a really hard time comprehending how I am suppose to know what basic social boundaries are. 