This love letter is going viral on twitter..know why!

New York: An apology letter by a student's ex-girlfriend has gone viral after the student from Stetson University in Florida, the US, broke the 'convention' by grading the letter and posted it on the micro-blogging site Twitter.

According to a report in CNET, Nick Lutz received a long apology letter from his ex-girlfriend where she tried to explain herself. 

But Lutz began marking the letter with red wherever he noticed mistakes of any kind.

On the first page of the letter, Lutz wrote in red: "Too long of an introduction. Lots of repetition."

When his ex wrote that she had never cheated on him, Lutz drew a red question mark and wrote: "Strong statement. No supporting Details to support your hypothesis."

Lutz, who turned 'an academic critique' for his ex-lover briefly, gave her 61 out of a 100 -- a grade of D-. The tweet garnered more than 100,000 retweets and over 300,000 likes.

"When your ex writes you an apology letter so you grade it to send it back," Nick Lutz tweeted with a photograph of the letter.