What is the ruling on speaking with a girl via social media with the intention of marriage, while current circumstances do not permit it, and should he leave her until his circumstances improve?

Islamic Sharia has warned against the temptation of women, and a man's conversation with a non-mahram woman is a great gateway to temptation. These conversations must be avoided, and communication with girls must cease, in order to preserve one's religion and honor.

If marriage to this girl is facilitated, then so be it; otherwise, there are many other women. A man must choose his wife well, and she should be righteous: "So righteous women are devoutly obedient, guarding in [the husband's] absence what Allah would have them guard." The best provision in this world is a righteous woman.

It is not sufficient to rely on knowledge gained through social media. Rather, one must ask trustworthy people who know the girl and have dealt with her, seek consultation, and then perform Istikhara (prayer for guidance).