Both love and fear have useful roles. Fear keeps people in check, as does love but from different angles. A leader must have a certain amount of control to lead - and the best leader will know how to manipulate these two to the best advantage to maintain control. One could argue that the ideal leader has what's best for the country at heart for his/her agenda, in which case, at some point knowing when to give up control might come into play. This isn't really what Machiavelli's book is about, however.
As Oberon also brings up indifference as well as hate, as extensions of love/fear, it begs to reason that the definition of these terms is important to your interpretation. While I wholeheartedly agree with his assessment in terms of physical altercations/primal reactions I am not so sure that it pans out in other scenarios, like national government. Too many variables.
I don't think that hate is the opposite of love. I would lean more towards apathy/control. Hatred is too focused on the object and too intense of an emotion to be the opposite of love. Dangerous, yes, but not necessarily the worst enemy. I think of hatred as dysfunctional love, apathy as being without hope and/or indifferent. In personal relationships control would be the opposite of love. As control is necessary to the ruler of a country I think we are mixing metaphors.
I don't believe that Machiavelli was really referring to 'love' per say, but leaning more towards affection, respect, etc. The reason it is 'safer to be feared than loved' is due to the intensity of the reaction when love gets distorted.