Ruining the friendship can lead down many paths.
In many cases it can end up with a sort of false sense of security

I suppose that really depends though...how do you see ruining the friendship? 

Does it imply things went south? Or rather that your friendship as you knew it is gone and replaced with something new...Is it better?
Is it worse? 

I found myself....I figured....I assumed...I hoped....Gave me a bit of a false sense of security in my case. Things didn't really get
rough until the end