A few observations, if I may:
-St. Valentine’s feast was taken off the universal liturgical calendar by 1969, so yeah, it’s now Saints Cyril and Methodius. But if you go to the Extraordinary Form mass, they celebrate St. Valentine’s day today (as they did where I went).
-St. Valentine’s day was never a really major holiday in the past to begin with.
-giving up candy is a personal discipline you have chosen for Lent, and however that works for you is up to you. A person might decide to give it up only every other day, or every day but Sundays, etc., etc., so the “rule” is only whatever you decided at the beginning. If St. Valentine is, say, your patron saint (i.e. name saint or something) I could see you celebrating today.
-the big popular holidays in America, for example, that happen to have saints names - like St. Patrick’s Day - do not necessarily correspond to the rank and importance on the Church calendar. For example, when St. Patrick’s day occurs on a Sunday, it simply is cancelled that year, yet people will still be celebrating it, as you will see.
-St. Valentine was a great saint, though.
