girlfriend season

The time period roughly between November to February, where a single person feels extra pressure to bring a suitable mate to holiday parties and family gatherings. This pressure often leads to picking the first available/willing partner. The forced relationship is often dragged out until just after Valentine's Day.

Another phrase for cuffing season.

(At a family gathering)
Cousin A: Who's that skanky girl holding hands with Brian?
Cousin B: No idea, never seen her before.
Cousin A: Well, it IS girlfriend season, I guess he had to bring someone.