Meant to encapsulate the cyclical process of some of the women who tend to circulate through boyfriends annually.
After being single or dating for most of the Summer. The Winter Coat Theory dictates that in the autumn season (usually around Halloween), they will pick a companion or boyfriend for the upcoming holiday events. The driving factors include to have someone to attend upcoming holiday functions (Thanksgiving, Christmas and New Years); to have some one to 'snuggle' next to when people tend to stay home more often (like it is cold outside).
The term 'Winter Coat' is an allegory meant to highlight the warm gained during these colder seasons.
Even though the abbreviated courting cycle may show early signs of incompatibility. The woman would tend to stay in the relationship till the end of the 'final' major holiday event - New Years. At which time, the cycle comes to its end during the Spring season.
The allegory of the 'Winter Coat' is used again, as the warmer weather becomes prevalent - Winter Coats are shaken off and stored away for the subsequent cold weather season.