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While many of us may have sensed it intuitively, there is now science behind the statement that "Love is all you need." A 75-year longitudinal study by Harvard researchers suggests that love is indeed key to a happy and fulfilling life.

While love seems to be a universally valued attribute, defining it in behavioral terms can be a challenge. As the Harvard study's lead researcher, George Vaillant, wrote of his team's findings, two essential ingredients are proven to correlate with a happy existence: "One is love. The other is finding a way of coping with life that does not push love away."

While many of us believe we would like to be in love, we face many hurdles in taking the actions that allow love to flow freely throughout our lives and relationships. We have many ways of defending ourselves against love and can struggle to give and receive love with ease, , and vulnerability.

With love being so closely connected to meaning and fulfillment, it's valuable for each of us to define love as an action or series of actions we can take to bring us closer to the people we value. In a romantic context, some essential characteristics that fit the description of a loving relationship include:

Expressions of affection, both physical and emotional.

A wish to offer pleasure and satisfaction to another.

Tenderness, compassion, and sensitivity to the needs of the other.

A desire for shared activities and pursuits.

An appropriate level of sharing of possessions.

An ongoing, honest exchange of personal feelings.

The process of offering concern, comfort, and outward assistance for the loved one's aspirations.

Love includes feeling for the other that goes beyond any selfishness or self-interest on the part of the loved one. As such, love nurtures and has a positive effect on each person's and sense of well-being. Love never involves , because misleading another person fractures his or her sense of reality.

So how well do we meet these standards for being loving? When we think about a relationship that is meaningful to us, we have to ask:

Do we both behave in ways that nurture each other?

Do we take actions to make the other person feel good?

Do we consider what lights that person up, separate from our own interests?

Too often, we think of love as an almost passive state of being, as opposed to a conscious choice we make. When we regard love as something we simply fall into, we can easily slip into routines with the person we value or lose a sense of separateness and respect. Instead, we view that person as a part of us. We then run the risk of creating a fantasy bond, an illusion of fusion in which real feelings of fondness and are replaced by the form of being in a relationship. In other words, we come to see ourselves and our partner as a single unit. We then fall into roles rather than appreciating each other as individuals and experiencing the exciting, loving feelings that result.

A bond offers a false sense of security—the illusion that we are no longer alone. However, when we connect to someone in this way, we lose our sense of vitality, and we give up significant aspects of our relationship. The behavioral operations of love are replaced with a fantasy of being in love, which does not nurture either partner.

Relationships tend to go south when we stop taking actions that our partner would perceive as loving and instead start looking to our partner solely to meet our own needs. It's important to distinguish emotional hunger from real love. Have you ever witnessed a parent hugging a child and wondered whether the hug was intended to comfort the child, offering reassurance and care, or to soothe the parent, taking something from the child? When we reach out to our partner, it can be valuable to examine whether our behaviors are for them or for ourselves. Are we looking to them to fulfill us in some way that is unfair to them? Are we hoping they will make up for an emptiness or hurt from our past?

A couple I worked with recently recognized an example of this dynamic. The wife would often compliment her husband, but he rarely felt acknowledged by her words. When she recounted some of the recent comments she made, she noticed that they were less of a reflection of him and more a reflection on her. Statements such as, "Aren't I married to such a handsome, well-put-together man?" and "Haven't I picked a winner?" didn't capture qualities that were important to him. They were traits she valued in a partner that reconfirmed her own self-esteem and sense of worth.

Love should never be an act of manipulation. It is not a mark of ownership over another person, but the exact opposite—a genuine appreciation of a person as a separate individual. When we see a person this way, we allow ourselves to fully value them for who they are and for the they bring to our lives. We are driven to be generous toward the person, to show compassion and kindness in a way that both they and the outside world would view as loving.

Of course, there are many barriers we put in place that not only keep us from finding this type of relationship but from achieving it with the person we love. One reason we wind up in less-than-loving relationships is the ways we were treated in our past. We may have become familiar with family dynamics in which we were rejected or intruded on, in which case we tend to seek out or recreate these same dynamics in our adult relationships. To become more loving thus means recognizing ways we self-sabotage: How are we recreating past hurts in our current relationships?

As we reflect on these behaviors, we learn a lot, not only about how we interfere with our naturally loving feelings for others but about the negative ways we feel about ourselves. It's difficult to express love outwardly when we don't feel our own sense of self-worth. One of the biggest reasons we shut out love is because we feel unworthy or self-denying. Therefore, to have a loving relationship, we must challenge our negative or critical inner voice. When we do this and take the loving actions that contradict our critical self-image, we enhance our own sense of worth and are able to get closer to the people we love.