What is your guidance and advice for girls who keep pictures of men on their devices and use them as their avatars in chat programs and forums, while being infatuated with these men?

For girls to keep pictures of non-mahram men or to use them as avatars involves several prohibitions, among them: the girl's heart becoming attached to the man, her looking at the picture with lust, and acquiring pictures for corrupt purposes. Therefore, these pictures should be disposed of as a preventative measure (sadd al-dhari'ah), based on the Almighty's saying: "O you who have believed, do not follow the footsteps of Satan. And whoever follows the footsteps of Satan - indeed, he enjoins immorality and wrongdoing. And if not for the favor of Allah upon you and His mercy, not one of you would have been pure ever, but Allah purifies whom He wills, and Allah is Hearing and Knowing."