Was it this?
Originally Posted by Emm
Would he be as willing to stick around if she was threatening to harm someone else if he left? "I'll kill myself" as a threat seems to be more socially acceptable than "I'll kill my neighbour", but really they're pretty much the same - an attempt by person A to hang a life on the line and make it person B's fault when the line breaks. In the latter case it's just more obvious that it's not person B's fault at all.
I still don't remember who I stole the concept from, so it may have been another post you saw.