Love is a human invention. Animals can not feel love, perhaps close bonding or loyalty but not true love. If this is true, then love can not be felt instinctively. That is because love is irrational , and unpredictable. But love is one of the most powerful motivations of mankind. It is an exclusive emotion we hold dear. Different forms of love also ensue within our societies as well. Love for your fellow man, love for your family, love for your spouse and love for your possessions. All of these loves are seen as requiring loyalty, some more than others.
But these loves also differ in ways such as the level of commitment needed, and the consequences for breaking such a thing. The amount of trust that is put in every time we love one another is so great, and so immense that if the trust is broken, it may cause some to be emotionally and psychologically scarred for the rest of their lives. Being back-stabbed by someone you love, your spouse breaking up with you or cheating on you, or even a loved one passing from this world to the next. These abrupt changes can drastically alter a person's view on love in less than a day.
Another aspect of what love is about is intimacy. It is believed that intimacy has a direct correlation with love. The more intimacy, the more love there can be. In spouse relationships, intimacy can be synonymous with sexual relations which is one of the closest intimacy-related exercises. However, sex is also a instinctive characteristic that is practiced by any sexual reproductive species. Only three animals use this method fundamentally: Dolphins, Chimpanzees and Humans. But humans take it a step further and in many modern cultures and for up until recently made it only socially acceptable for sex to be for a monogamous relationship solidified in matrimony.
Is this in fact what love is? No, it is the rewards of sex, and not the action, that defines this kind of love. The monogamy and trust between partners is what is held so sacred in sex. Though in many religions, it is an unholy sin to commit this atrocity out of a single bond of a man an woman for intimacy and procreation within their marriage. Why? Sex is so sacred that it seems too powerful for even humanity to resist their own animistic instinct. If you have ever noticed, religions/beliefs/sciences bring humans closer to godliness and further from animals. But we will never achieve it because the key to our race is an instinct and our progress is artificial. And the same can be said for love.
In short: Love is a mixture of humanistic characteristics that bring us closer to Utopia with the animistic instincts that tie us down. But these instincts give us the motivation, where the human-made emotions give us the focus. That is why love is such a sought after and beautiful thing, it encompasses hte worlds of our past present and future, defining the human race. Love, a fairly new concept within both marriage and human kind. Let us hope we do not squander such a thing.