What is the way to get rid of feelings of exhaustion, distress, and mood swings resulting from loving a girl and desiring to marry her, given the obstacle of not having finished studying?

The solution lies in distancing yourself from her, as you have exceeded the Shari'ah limit in communicating with her. It is not permissible for a Muslim to be in a relationship with a woman who is a stranger to him, or to converse with her, except for a legitimate need and within Shari'ah guidelines. For peace of mind and tranquility of heart, cut off all ties with her. If marriage to her becomes possible in the future, then so be it; otherwise, Allah has created many women.