Hate is not the opposite of love--hate is the frustration of the drive for love.
The real opposite of love, as Trippin suggests, is indifference, which is the withdrawal
of emotions. (It's very difficult to help people who have no emotions.)

In one sense, that's why it's so funny that we can get so upset when there is emotional upheaval going on. Emotions are natural; it's the lack of any emotions that is unusual and disturbing.

We tend to associate strong intelligence with calmness of the emotions--that is, the
emotions don't get in the way of our thinking. That is the nature of bipolar illness: the emotions get in the way of thinking for many. It's the stability of the emotions or moods that science hopes to stabilize.