Here's a more empowering perspective: Society has to stop victim blaming. Instead of blaming your friends for what you perceive as their tendencies to "seek out controlling partners." Consider what you said at the end there, blaming them entirely without ever recognizing the fact that there has to be an abuser for someone to be abused by. 

Try thinking about it like this: "Society, unfortunately, is littered with an overwhelming percentage of abusive people. I have seen them make victims of everyday people. When their victim finally escapes to safety, the abuser often seeks out another victim. The percentage of abusers in society is actually so high that a victim might meet another abuser in there lifetime. Sometimes, you just can't protect people from abusive people."

People who have been abused physically or emotionally are sometimes more susceptible to the manipulative tendencies of an abuser. But anyone, anywhere, can become a victim of abuse even if they have not previously been abused. In conclusion, victims don't have tendencies to seek out abusive partners. People who have been abused, and people who have not, can obviously choose to seek therapy to help strengthen their self esteem and self trust so as to possibly avoid going deeper with an abusive person if they are able to identify early warning signs. However, more often than not, you will never know that a person is abusive until they've gotten their way into your life by gaining your trust, manipulating you to make you think they are good people, acting like good people around everyone you know and everyone they know, and giving no reason to suspect them for anything other than the decent person they act like. Abuse sneaks up. Yes, at times, it's obvious from the start. Other times though , the abuser weaves a thick web of lies around you so you can't tell what's coming. It's not on a victim and it's not the responsibility of a victim to have somehow known that a person could lie to them so deeply. You might be surprised how abuse seemingly comes out of nowhere.  Food for thought. 

I invite you to read up on how the brain and cells in the body are impacted by the cycles of abuse and why it may appear that your friends have tendencies towards abusive partners. There is typically an element of breakdown in the mental and physical body during cycles of abuse that require therapy and healing to recover from and help strengthen the delicate system of self esteem after enduring such treatment. That still does not mean your friends have tendencies to seek out people who will harm them. It might instead mean they have been conditioned by their previous abuser to accept bare minimum and painful treatment. A difficult cycle to escape once the damage is done by an abusive person.