What is Mistress Day?
As defined by Urban Dictionary:
"The day before Valentine's day typically reserved for a man taking out his mistress or girlfriend. On Valentine's Day a man is "required" to take out his wife or steady girlfriend. However, the restaurants, bars and clubs are packed on February 13th for the better looking women in a man's life.
Mistress Day gifts are typically always jewelry and lingerie, while Valentine's day gifts are chocolate and teddy bears.
The most popular day for "short stay" hotel bookings."
No anyone going on tonight you love? Maybe, double check what they're up to.