Because the internet demands lists and manufactured controversy, herewith is a ration of both: Valentine's Day Should Be Abolished, and You're Doing It Wrong, Anyway.
1. Every day should be Valentine's Day, if you're in love. Every day you should come home with flowers and a box of confections and a card that has a picture of an important circulatory muscle, stylized so its ventricles resemble the gentle hillocks of a Grant Wood painting, or cleavage.
2. If you do bring these things home every day, though, the other person might say, "You're spending $9.50 a day on cards with pink and red depictions of a fist-sized organ. Do you know what would happen if you saved that money? Have you heard of compound interest?"
"Yes," you respond lovingly, "but you buy two soy lattés every day, and they cost at least that much."
"That's coffee. Coffee is important."
Weeks later, to girlfriends: "He complains that I buy coffee! He's so controlling. And cheap." (Friends all nod sympathetically, because they never liked you.)
3. It sets up unrealistic expectations. If your relationship is in a state that intersects with your first Valentine's Day, everything's over the moon and it's wonderful. But to be honest, you could share National Neuter a Ferret Day and it would be magical.
If the relationship has been going on for a while and you have attended at least two weddings as a couple where a drunk uncle said, "So, you two are next, right?" and you both felt your faces pucker, this will be the Valentine's Day you don't talk about getting married.