(n.) the condition of a semi-forced, semi-serious relationship resulting between two people who are going to prom together. This normally includes texting, brief hangouts, and any other activities that would "set up" the night of prom. Normally, such a relationship lasts from the instant when the dates decide to go together until the morning after prom.
The instantaneous "break-up" that occurs between two people the day after "getting together." This normally unspoken end occurs between people who have been "prom dating" or who have just engaged in a one night stand. This breakup is normally entirely mutual and amicable.
Could also refer to a rather malicious end initiated by one person to a brief, one night romance.
Person 1: Hey, what happened with that Alice girl last night?
Person 2: Eh, we had fun, but it ended with a wake-up break-up