To answer the first, “How long can one live with Objectivism
holds that for each person his own life is his ultimate value. Morally, the greatest thing one can do is to live robustly and to keep living. Happiness, in the Objectivist view, is the emotional experience of living well. Happiness is not a state one achieves, but the experience one has in the process of living a flourishing, robust life. Happiness is a complex emotion, involving many rather different subsidiary emotions, such as contentment, confidence, satisfaction, excitement, joy, and good cheer. These emotions generally proceed from achieving one's values, as when one feels joy and satisfaction over completing an important project, or as when one feels content after a good dinner. Happiness also proceeds from one's self-esteem, one's general sense that one is competent and worthy to be successful in life.
In any case, there isn't any before and after. Living happily is something one does, and that one keeps doing. If one is living at all one may experience at least glimmers of happiness, and if one is living well one is likely to experience a rich and full happiness over the course of long, healthy life.
How long can one live with Objectivism
? As long as it is possible to live by the best techniques for living known to man.
As to the second question, “How could one trade love?”:
Love is an emotion. One cannot trade the emotion, obviously. It's not possible to literally transfer an emotion out of one's body.
But a relationship in which there is love is based on trade. The relationship consists in doing things with another person that you both value. In a romantic relationship, we trade our time, regard, and consideration with the loved one, and receive in return the values of visibility, affection, and consideration that the other offers in return. In romance the visibility in particular can be very intimate and total, and the expression of one's regard can also be highly intimate as well. In its fullest sense, romantic love is a response to a full person, including both mental and physical traits. But it is a response that occurs in exchange with another. It really does take two to tango, as they say.
Consider by contrast a relationship not based in a general sense on trade. This is one (and perhaps you often observe such) in which people fulfill their social duties to one another without affection, or in which one takes and gives nothing back. How can there be love in any real sense in such a relationship? As Ayn Rand
wrote in The Fountainhead
: “To be able to say 'I love you,' you must first be able to say the I.” So to be a lover, one must hold oneself worthy of love. And indeed, who is doing the loving, and who is being loved, if there is no trade of values in the relationship?