One of the most commonly asked questions when discussing abuse 
is " Why doesn't she leave?" instead of "why is the person 
abusive?"  The focus is often on the woman's behaviour instead 
of on the abuser's behaviour. We call this victim blaming. 
It implies that the abuse is the woman's fault and that 
there's something wrong with the person if they stay in the 
relationship.  Women stay in abusive relationships for 
many reasons. Some of these reasons include...

o you hope your relationship will get better 
o you hope your boyfriend  will change his behaviour
o you are afraid you will be hurt if you try to break 
  up with him
o you feel guilty or ashamed about the abuse or blame yourself 
  for it
o you don't know what to do, don't know your options or how to 
  get help
o you think abuse is normal or tell yourself it's no big deal
o you believe having an abusive boyfriend is better than no 
  one at all
o you share the same friends and are worried you will lose your 
  friends if you break up with your boyfriend
o you are isolated from the support of your friends and family
o your boyfriend has threatened to hurt you or themselves if 
  you leave them
o you are afraid people will blame you or not believe you
o you love him and believe he needs you to help him
o you don't want to lose the status of being in a relationship
o you have low self esteem due to the abuse and blame yourself 
  for the abuse
o you feel it's your job to fix the relationship
o you feel it's not the right time

There are many reasons people stay in abusive relationships.  
It is easy to judge others who stay in abusive relationships.  
It is more difficult to support women and let them decide for 
themselves what to do and who to tell. Supporting is far more 
helpful to women than blaming them. The only person to blame 
for the abuse is the abuser. Leaving an abusive relationship 
can also be dangerous. Thought and planning should be done 
prior to breaking up with an abusive person.  Overall, 
leaving any relationship takes a lot of courage, and it takes 
even more courage when violence is involved. 

See safety planning in Safe Dating Tips if you are planning 
to leave an abusive relationship.