Emotional availability is always a rare and beautiful thing when encountered in others. Actually being open-hearted oneself often seems to be an invitation to manipulation, abuse, and rejection. This is because the heart (as an emotional center) is a doorway to compassion, which involves delving into the Sea of Infinite Sadness that is the sum total of all life's experience from the ego's perspective.
Compassion incorporates the awareness that all we do as living creatures is only the tiniest blip on the cosmic radar, that all human achievement is temporary, and that any individual's actions may therefore feel entirely futile; in addition to which most people who recognize an empathetic person will express firstmost their misery and disappointment. The goal of compassion is to move beyond this egocentric 'poor me' point of view to an enlightened state of connection to a larger sense of self. However, not only is it easy to slide back from this heightened awareness into the depths of personal discontent; it is also just as easy to keep this illumination localized in the safety of the mind where it can exist in an Ivory Tower, disconnected from the heartache and suffering of life.
Yeshua ben Josef (a.k.a. Jesus Christ in vulgar Latin) is an example of one who struggled to use his compassion to alleviate suffering by bringing others into an enlightened state; the prolonged gore of his assassination shows how much this was appreciated at the time. Conversely, the Buddha Siddhartha Guatama managed to live and teach longer than three years, partially because he started out as a prince rather than a carpenter, but mostly because he was born on the right side of the planet. At any rate, the lessons of these and all other transcendent sages, martyred or otherwise, suggest that we as human beings have the opportunity to release this attachment to suffering, and thereby conquer the death of the ego. So what is it that keeps ordinary schmucks like you and me from bringing it all together and evolving into spiritual masters? In a word, karma.
Karma at a practical level isn't about justice, or past lives, or even the balancing of universal energies. It's about recognizing the patterns and laws by which one leads one's life and seeing their inherent falsehood and limitations. Most of us fail to comprehend just what is meant by 'attachment to suffering.' Over the course of any lifetime, when bad things happen it is normal to learn from the experience. Unfortunately, this learning process is seldom conscious, occuring as it does primarily at the level of emotions and beliefs rather than at the level of rational thought. The lesson is then incorporated, which is to say, brought into the body at a cellular level. Once this is done, reality is defined in terms of that lesson.
For instance, a child who burns his hand may be sufficiently traumatized by the experience to develop a fear of fire. Fire may become a symbol to that child of all that is evil and hurtful. As an adult, this person may be able to rationally use a lighter or a stove without flinching, but may also believe in an afterlife where the soul is burned for eternity for being evil. This fear will continue to severely limit the person's ability to accept the diversity of human experience unless the root of it is brought to light and an alternate belief is engendered.
Furthermore, this new belief must be sufficiently impactful to negate a whole lifetime of living by the previous belief. For this to occur, one needs open-heartedness. Without it, any new lessons are just flotsam and jetsam on the stream of consciousness. This doesn't necessarily mean accepting the abuse and miserable company of those that see empathy as weakness. Everyone needs to be able to retreat to a safe place, away from social manipulation. In this space, one may see how the ego's Sea of Infinite Sadness exists as a mere drop of water in the Universal Self. Gradually, this awareness may grow strong enough for the individual to invite others to share it. When this is possible, it will signify an integration of Higher Self with personal identity. Only then will loving kindness result in bringing others up without getting entangled in their suffering.