I regularly post as 'Ian cookieless' but I am not the 'cookie-less' originator of this thread. I am single, too, and at times like Valentine's (when, as you say, friends in couples are doing Valentinesy things) I might go and see my aged parents, read a completely absorbing book, go for a long walk somewhere stunning and bracing, go to a folk club ... In other words, occupy your mind so it doesn't wander onto your feelings of being alone on a day meant for couples.

Naughty P.S. I might also think of a past partner where things ended badly and just be glad I don't have to suffer *her* on Valentine's Day!