Everyday gratitude serves as a booster to romantic relationships and binds couples together. Check out these resources to learn more:

It's the Little Things: Everyday Gratitude as a Booster Shot for Romantic Relationships. (journal article)
To Have and to Hold: Gratitude Promotes Relationship Maintenance in Intimate Bond. (journal article)
What is Gratitude? (essay)
Why Does Gratitude Matter?
Robert Emmons, the author of Thanks! introduces the science of gratitude at the Greater Good Gratitude Summit in June 2014. (video)
Why Gratitude is Good. (essay & videos)
How Does Gratitude Affect Romantic Relationships?
At the 2014 Greater Good Gratitude Summit, Dr. Sara B. Algoe describes her research into how gratitude affects romantic partners’ feelings for one another, as well as their style of relating to each other. (video)
Love, Honor, and Thank
Researchers Jess Alberts and Angela Trethewey have found that a successful relationship doesn’t just depend on how partners divide their household chores, but on how they each express gratitude for the work the other one puts in. (essay)
Gratitude (group ice breaker)
Based at the University of California, Berkeley, the Greater Good Science Center studies the psychology, sociology, and neuroscience of well-being, and teaches skills that foster a thriving, resilient, and compassionate society.