Sexual attraction is natural, and so is masturbation. However, if either of them is causing you to spend excess time thinking about it or doing it to the extent that it is affecting your routine, you need to seek professional help. It is not healthy to be preoccupied only by sexual thoughts, causing one to do something drastic or lose touch with reality. It can also cause one to avoid connecting with people and forming meaningful relationships in real life, while pursuing a virtual/fantasy relationship. If this preoccupation is affecting your work, health or quality of life, please seek professional help at the earliest.