Earlier we looked at how not all things called "love" are really something that Christianity can recognize as the kind of love that Christ had for his people, the kind he enjoined us to have for each other. That is no longer the question here.
The next question on the table is whether a genuine love -- one that truly cares for the other person -- always justifies sexual consummation. Pre-marital sex? Adultery? Betraying a mate, revoking promises of faithfulness, abandonment of children? These things are tragic but not inherently wrong in most secular sexual ethics. The answer often given to whether love always justifies sexual consummation is "yes, so long as there is consent". As we have already seen, some questions at stake are these: Am I an isolated individual, or do my actions matter to other people? Does relationship damage count as harming myself or others? When we are talking specifically about the ethics of sexual consummation there is another root question to consider: What is its purpose?
On one view, sexuality is about human survival. Sexuality is the procreative act: it makes children. Pleasure and desire are means towards this one end: creating another human being.
From a Christian view, the pleasure and desire are God-given benefits that aim for an even greater end: another person, intrinsically worthy of the type of love that Christ enjoined, the type that loves other people not based on their usefulness but based solely on shared humanity. The creation of another person in the image of God is considered an inherently good thing, a child considered an occasion for gladness. From a Christian view also, the pleasure and desire are rightly part of a family bond, which is the stable basis on which a person can know he or she will always have love in this life.
In popular culture, the purpose of sexuality is considered to be pleasure, the satisfaction of desire, the relief of a hormonal pressure, or even (though not necessarily) an expression of genuine love. The purpose of reproduction is often denied or frustrated at all costs. While doing the one act that naturally produces children, some camps seem continually annoyed or surprised when a child results. Great pains are taken to ensure the sterility or chemical-induced infertility of one or the other persons involved, and as a fallback, if a child does result, the new life is not typically welcomed or valued but often quietly ended. Obviously this approach to sexuality is not a great advantage in the survival of humanity; cultures which have adopted this "ethics" have seen their populations on the decrease. As has also been much discussed, this approach necessarily degrades the value of humanity when the shared humanity of a new life is no longer considered sufficient basis to welcome that life, and its very right to exist is denied on such a profound level that no questions are asked before the life is ended. Love for the partner may or may not be removed from sexuality, but it is removed from reproduction, and from humanity at large. Sexual union is degraded from an act with life-long consequences and the power to create life to nothing more than an intense pleasure. Neither is there any way to devalue the meaning of sexuality like this without devaluing ourselves along the way, since our sexuality is an important part of who we are as persons. Sexuality is such a basic and important part of our lives that removing love from sexuality often threatens to remove love from a person's life, and removing long-term stability from sexual partners removes long-term stability from a person's life. Neither is there any way to ignore the reproductive angle of sexuality without devaluing families, since sexuality and procreation are the basis of families.
A view of sexuality which takes no account of family bonds necessarily devalues family bonds and leaves large numbers of people lonely and adrift. A view of sexuality which takes no account of procreation -- other than avoiding it -- necessarily leads to devaluing the family, impoverishing many lives of meaningful and lasting relationships, and depriving many people of a personal stake in the future of mankind. Sexuality has a large and important role in our life: family, children, and a stable life-long bond. This means that love -- even genuine love -- does not automatically justify consummation. It also means that the ones who suffer the greatest losses from sexual irresponsibility are the person deciding to go for it, and his or her beloved. A genuine love, realizing this, might reconsider.