These are cross quarters and are used in "pagan traditions" which is why the Catholic Church was eager to "set up" on one. (Note that February 2, is Imbolc/Candlemas) Groundhog's day is closer to German witchcraft in origin, so the common overlap can be seen there. They are not exclusive to paganism, but what is being asked about concerns origins that are rooted therein for the nature of the question.

Both of them occur in the sign of Aquarius, and Aquarius is about "Groups of people or tribes/beliefs". Usually you sow spiritually in winter and reap in spring, and both of these holidays are aiming to establish something about the head of the year. (i.e. March by that reckoning) We can do a little better if we understand Aquarius as the sign of "love of humanity" in a spiritual sense where Valentine's day is concerned. Therefore, the idea is to twist that love into more of an eros derivation as opposed to a "general agape". It is a kind of gnostic trap which turns love into an ego desire fulfillment.

Groundhog's day utilizes the shadow of an animal that lives underground that is called, of course, a hog. Hogs are usually considered to be unclean, but the idea is that when the weather warms up from winter or else changes from being very dry in other parts of the world this can be deduced in Aquarius and so both are aiming to have a mass effect. (Commander Shepherd feels this somewhere deep in space) Valentine's day misdirects knowledge to personal eros, and Groundhog's day is doing something where the underworld influences the faith about the timing of the season of spring and both are rooted in mercy. (The idea of praying for rain/heat are almost as old as humanity, if not older)

Probably, the best concept for Groundhog's day from an understanding perspective is the movie by the same name where the main character wakes up trapped in the same day over and over until he learns to do something different. (He receives no mercy in effect or the mercy is a chance to figure out how to stop what he doesn't like but he dies many times in the process) He always wakes up in the same town, and the same day happens over and over. He tries of course to control it by controlling the groundhog. This doesn't work. In a round about way, these holidays are time hacks trying to get all of humanity to fall into certain kinds of patterns based on traditions with questionable aims. The midway point between seasons is less relevant in a sense here. The thing being highlighted is that Aquarius is an energy that determines what happens for masses of people, and the default is supposed to be set on mercy, or they would never get rain or out of winter. Both holidays try to do something so masses of people are somewhat distracted where those issues are concerned.