The life force energy that flows through us during lovemaking not only propels us into all sorts of important life experiences via relationships, it is powerful enough to create new life! This same energy can carry us into blissful states of consciousness during spiritual practices such as meditation. As it is powerful stuff, it is very important that we use it wisely.
This doesn't mean we should become ascetics. If we don't use our life force energy enough, we end up depressed, sluggish, bored, listless, and physically ill. If we use it too much, we end up exhausted, burned out, stressed, anxious and physically ill. As with everything, balance is wise. Good health, personal power and happiness all depend on a healthy balance of chi. When used consciously, this force is the source of all art, innovation, growth, creation, progress, life, etc.
Every interaction between people involves an exchange of energy. When that interaction involves profound feelings of love and desire (or bodily fluids!) the exchange is intense. Just kissing and heavy petting create energy links between the parties involved that penetrate their auras. These links are temporary, however, and will fade away in a few days, weeks or months, depending on how much mental and emotional energy is fed to the connection after the sweethearts physically part. Sexual intercourse creates a much stronger energetic bond on the astral plane that will often last for many years. The more emotionally and mentally involved the lovers are, the stronger the link. It is this energetic connection that causes emotional pain upon separation from a lover, for it's like a living part of them is starving to be fed.
The more intense a relationship is, the stronger the bond is. The more times we have sex with a certain individual, the stronger our energetic bond will be to them. That's why it's so much more painful to leave someone we're in love with than someone we don't really care about, and why even leaving a "dead marriage" can be so darn hard - those energetic bonds are very strong due to many years of sustenance.
Now to explore the effects of promiscuity, let's get past all the confusing moral lessons we've been taught by working with an ecological metaphor. We know that if we're careless ecologically, the Earth is affected in undesirable ways. Being careless about whom we sleep with is like being careless with our natural resources. If we use them up before they've been replenished, we end up depleted. If we fail to treat our bodies as our sacred homes, they end up deforested, polluted, scarred and littered with garbage. When it comes to sex, the key to maintaining one's vitality and beauty both physically and aurically is thus to treat our bodies and sexual experiences as sacred. This doesn't mean we should only have sex within legal marriage or anything like that. In fact, in some ways the determined "security" of marriage often makes it very challenging to keep sex a conscious spiritual act. Everything that happens on a physical sexual level has correspondences at a metaphysical level, so every time we have sex with someone, we know we're mingling with their physical germs, but we're also mingling with their emotional, mental and spiritual "germs", PLUS the energetic issues of the people they're connected to.
Since the sexual revolution, the energetic webs between people have multiplied unlike anything ever seen before on planet Earth. Every time we sleep with someone new, we are linking with everyone they've ever slept with both physically AND energetically. From the astral, this is seen as a vast web of intricate energetic interconnections. Further, it's not necessary to have physical sex to experience a strong energetic bond with someone. The deeper you feel about someone, the deeper your bond to them - even if your feelings are hateful instead of loving. If you feel a very deep, strong connection to someone and fantasize about them often but never sleep with them, you may have a stronger auric link to them than a prostitute would have to her client.
Though culturally we've twisted sex around to the point where common attitudes are a universe away from spiritual truths, beneath some of our moral 'values' there is some real wisdom. For example, virgins (both male and female) appear aurically "pure" and beautiful because they are free of energetic cords. They aren't caught up in that vast web described above. They are also guarded by an energetic, hymen-like shield that protects them from psychic intrusion. While I certainly don't appreciate the way we've smeared this simple truth with religious guilt and the economics of procreation, there is some spiritual "value" in being a virgin just as there are "risks" in being sexually reckless.
As we grow more and more spiritual, we naturally grow more and more mindful in every area of our lives. Mindfulness is the key to growth and greater well-being. The more mindful we are about what we eat, what we think, what we read, what we believe, who we associate with and yes - who we make love to - the more we will be able to manifest personal power, fulfillment and well-being. To me, this doesn't necessarily mean we should restrict ourselves in any way. Instead, we should bring our highest selves to every relationship. We should remain very conscious about what we really want and use our personal gifts and resources wisely. Whether we're talking about sex or any other matter, to manifest a happy, healthy life experience, we have to consciously bring the best of ourselves to all we do.