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(THE CONVERSATION) Valentine cards are filled with expressions of unequivocal adoration and appreciation. That’s fitting for the holiday set aside to express love and reaffirm commitment to one’s romantic partner.

But what if there’s more going on below the surface of these adoring declarations? How might thoughts and feelings that people are not even aware of shape their romantic relationships?

We are two psychology researchers interested in how the mind works, and how it affects...