Q: Why is it that instead of enthusiasm, I suddenly feel complete indifference?
A: Any person who begins to be aware of the purpose of creation, the attainment of Him and the means to do it, is in fact being given an invitation from Above to study the wisdom of Kabbalah. The rest is up to you.
Whatever you feel (and it doesn’t matter what it is, because you’ll experience many different feelings, ranging from complete indifference to anxiousness) is given to you so that you can advance. Therefore, the only answer is to go on studying diligently, regardless of your changing moods and desires.