What is the ruling on a young man conversing with a young woman via social media for the purpose of marriage, and what is the punishment for that?

It is not permissible for communication to occur between the two genders via social media for the purpose of love and marriage, because it is a source of temptation (fitna) and leads to falling into the unlawful (haram). Whoever desires marriage should approach houses through their proper doors and propose to the girl's guardian, as the Prophet, peace and blessings be upon him, said: "Nothing is seen for two who love each other better than marriage." The default rule for communication between the two genders is prohibition, except out of necessity and with controls that prevent temptation. As for the punishment for this act, Ibn al-Qayyim mentioned that whoever loves something other than Allah will be punished by it three times in this world (before obtaining it, while obtaining it, and after being deprived of it), followed by punishment in the Barzakh (interim period after death) and in the Hereafter.