No doubt that sin hurts God, but don't forget to consider your own soul. Every time we sin, we mark our soul with a black stroke. When we commit a serious sin, it would be like marking the soul black with a big, broad brush. Eventually, if we don't repent and/or go to confession, the soul will appear all black and soiled. That surely would be an ugly sight repugnant to the Lord and at the same time making him feel even greater pity for you.