I've noticed a trend where more and more single folk I know have begun spending Valentine's Day going out with increasingly large groups of platonic, often same gender friends. How many evites, facebook events, or random invitation emails have you gotten for these things?
I think it's just social aspects of evolution. Maybe it's defensive schooling or herding instinct, or perhaps ingrained pack hunting skills. Who knows. Just remember to drink less than the person you're buying drinks for... unless you like waking up the next day with strangers in your bed.