My dad died when I was in 5th grade. While he was around, my parents were in an on-again off-again relationship (the off-again usually caused by physical or emotional abuse by either party). Don't get the wrong idea, they were together more than they were apart, they only separated 2 times that I can personally remember, once for several months and once for a few weeks.
I constantly find myself in destructive relationships that never end mutually. Examples: one girlfriend cheated; one girlfriend turned out to be a schizophrenic (literally); one girlfriend was ridiculously obsessive (meaning she would call upwards of 80 times a day, starting around a week and a half into the relationship).
On another level, I'm a bit self-destructive when it comes to who I'm attracted to. The people who I attract (who want to date me) tend to be good friends of mine, but I have no sexual attraction to them. On the other hand, the people who I am attracted to tend to be in relationships (about 90% of the time) with a good/decent guy, and both people are normally good friends of mine.
These are all things that I'm willing to talk to almost anyone (meaning most of my friends) about, except for someone who I'm attracted to.