It depends on how the relationship is going, if this relationship is a toxic situation it will definitely effect your health. Some of the symptoms are always stressed, extreme anxiety, mood changes and sleeping problems. To fix this, simply cut off the other person or if possible, try to fix things.
I would think it would depend on the situation. Basic first aid may be all that is required for certain wounds or accidents. In other circumstances it should be administered until a trained professional can take over.