snowball

Snowball is the opposite of scrooging, it means someone is trying to have a girlfriend / boyfriend / significant other thru Christmas and New Year's but will suddenly drop them after the holidays. 

Snowballing also refers to a certain sexual practice, but it more commonly means something that is increasing, accumulating, expanding or multiplying at a rapidly accelerating rate. For example, a trend that has begun to snowball like "one of those games in which things just snowballed and kept getting worse for the home team."