True love is care about another as if they were you (assuming you cared about yourself). Neither person is more important than the other. It is a perspective that transcends and includes both individuals'.
Sexual desire is not love. At best, it is the icing on the cake of love. When you say "I love her/him" but really mean "I sexually desire her/him", you cheapen love. When true love exists, sex is not perverse, and you don't have to worry about others judging it to be perverse because you know that the foundation is true.
Obsession and infatuation can result from an emphasis on the sexual or self-pleasure aspects of relating to someone else. You are not interested in the other person so much as how they can make you feel good. This is definitely not love because the moment they don't do or be what pleases you, it turns into anger, disappointment, or resentment.
A good relationship begins with love. Though infatuation may spark the initial encounter, you must quickly curtail your automatic reactions to it so you can concentrate on the selfless, transcendent perspective and build a solid foundation. Otherwise, the termites of resentment and manipulation will compromise the building relationship no matter how wonderful and glorious it appears right now.
Manipulation includes distracting yourself from sexual frustration with your object of desire by fantasizing about others or pornography. Though your sexual aloofness appears like transcendence, it really is just sweeping the frustration under the rug. It will creep up later in the relationship in the form of infidelity and not being present to the other.
More commonly, manipulation occurs as you want to maintain a steady supply of short-term self-pleasure at the expense of the other and the relationship. You don't even think about whether something is good for either of you in the long run, just how it makes you feel right now and, secondarily, how pleased the other appears right now. You trick yourself and your object of desire into thinking an action or attitude is fulfilling when it is really just a series of brief highs followed by a let-down, eventually spiraling into the big let-down of a breakup.
True love between individuals is the building block for true love between groups and nations. So long as we myopically seek immediate gratification at another's expense, we all suffer from being similarly used. As helpful as this selfishness has been in our evolution, we must learn to shed it and adapt to our new understanding of the inescapably interconnected environment.