By definition, an unreturned love is one-sided. But doubtless, the experience itself embodies two sides. On the upside, you’re enthralled, charmed, and captivated by the beloved. Your passion for them is exhilarating: an incomparable high. Regrettably, the downside of such ardor is every bit as intense—replete with agonizing feelings of loneliness, misery, and despair...