Is it permissible to correspond with a girl online with the intention of proposing, given that there are current obstacles preventing the completion of the engagement, and out of fear that the girl might forget you or that someone else might propose to her?

If a man loves a woman, he must keep himself pure from what is unlawful and strive to marry her if she is righteous, for the Prophet, peace and blessings be upon him, said: "There is nothing better for two who love each other than marriage." If marriage is not possible, he must completely cut off the relationship with her to avert the trial of women, which is among the severest trials, as the Prophet, peace and blessings be upon him, said: "I have not left behind me any trial more harmful to men than women." So he should avoid her and be patient until Allah facilitates marriage for him. He should generally hasten to marry, as it is a ritual and an act of worship.