The thing about heart aspects is that their loved ones are literally their weakest point but also their strongest strengths. I have seen a couple theories that heart aspects have a “beserk button” like the rage aspect.

That button is messing with, including injuring or killing someone who is close to their heart.  They will try to get you back for it until they feel like the score is even. 

They are not afraid to kill you in the process or die trying.