I've had two long (12 years) and lovely marriages, many other relationships and zero Valentines cards!
My second husband, being from an exotic country, couldn't get his head round all the cards we send anyway. ('Do I have to buy a card for Bonfire Night?') I challenged him one Valentine's Day and he said, being a quick and witty thinker, 'But I love you every day of the year'. Try it - it worked for me. (Before you say the obvious we are still very close.)
Jezzay