It sounds as if your girlfriends daughter has picked up on the stress that her mum is going and has gone through. If your girl friend can begin to relax more in front of her little girl then the bed wetting etc will most likely cease. Children younger than this can pick up all kinds of negative emotions and it will be having an affect, she is quite obviously wanting to make sure her mum is ok and wants her attention. Ask your girlfriend to try and give her daughter more attention by playing with her as much as she can and cuddling her. I'm sure once your girlfriend has got over this dreadful period in her life she will be fine, with a boyfriend like you to support her how can she go wrong! Keep up your good work.