8 things that happy couples have in common

• With Valentine's Day just around the corner, happy couples seem to be all around us.
• But whether you're in a relationship right now or not, have you ever wondered what has made you and your significant other so happy?
• eHarmony released a new study discussing the happiness of couples in America.
• INSIDER spoke with eHarmony's Chief of Advice to get the scoop on what the secrets are to a happy relationship.

Hearts, candy, and roses have overflowed the store aisles. Love is in the air and it seems like more than ever, smiling couples are all around us these days. Very appropriately and just in time for Valentine's Day, a national report discussing the happiness of couples in America was released.

The study titled "The Happiness Index: Love and Relationships in America" was commissioned by eHarmony. More than 2,000 interviews were conducted by Harris Interactive with participants who were either married or in a long-term relationship andover the age of 18. The results were weighted appropriately to be nationally representative by age and gender.

What they found was that 64% of Americans are "very happy" in their romantic relationship with their partner or spouse and only 19% are unhappy to some degree.

To find out just what exactly makes a happy relationship, INSIDER spoke with Jeannie Assimos, Chief of Advice at eHarmony, who shared these couples' best-kept secrets.

Secret 1: They’re millennials.

That's right—millennials win. Those between 25 and 34 were found to be happiest in their relationship, according to the study’s press release. 

Secret 2: They possess certain attributes.

According to Assimos, couples with certain personality traits were happier than those without these qualities. She said both partners in a happy relationship were found to be creative, confident, sociable, and optimistic.

Assimos explained that these characteristics contributed to the success of their relationship.

"It all makes sense that those people are going to be happier. They're optimistic about life. They're open and more authentic about who they are," Assimos told INSIDER.

Secret 3: They have a combined income of $200K.

The survey found that those with the highest household income reported the highest level of happiness and satisfaction with their relationships.

Assimos said she was not surprised that money factored into happiness. Knowing that financial stress is such a negative influence in a relationship, it made sense that those who didn’t have to worry about finances had more time to focus on putting time and energy into the relationship.

But don’t lose all hope. Assimos told INSIDER that money isn’t everything. While 71% of couples who made $200,000 said they were completely in love with their partner, those making less than $30,000 per year came in at a close second at 65%.