Speaking from personal experience, it's hard to not dwell on something when every day that one thing is pretty much waved in your face through interactions with others, and then there's two days out of the year dedicated to that one thing (one for him, one for her), and a couple of weeks lead up those days which everything marketing ploy in the book aimed at those days.
You try and move on, but there are just times when you get roundhoused in the face by it.
Not arguing what you're saying, because it seems like you get the "what's the harm" point of it all, but just providing examples.