If I forget to lock my door and someone robs my house it is partially my fault, but a thief is still a thief.
Yes, the thief came inside because of your partial fault - if not he would not rob your house and if you do it repeatedly then it becomes more and more of your fault. Do you want to avoid the thief coming in or once he is done it, do you want to get the cops involved and then the court and lawyers to make it a circus.