"Boyfriend" is not short for anything. It is a single word.
While "boyfriend" is a complete word, it's often abbreviated, especially in informal communication like texting or online messaging. The most common abbreviation is BF. This doesn't mean the full word is short for "BF," but rather that "BF" is used as an abbreviation for "boyfriend."
Therefore, "boyfriend" is a complete word and not an abbreviation.
