You have no evidence that she is either inconsistent, or unpredictable. While there is the occasional T who becomes overwhelmed by counter transference, or the realization that they don't have the skills to help a client, or by a volatile relationship that becomes destructive, most do not turn into overnight monsters. Most of the time it is our defenses which distort our perceptions, interpreting actions according to our fears. This is exactly the challenge of therapy: to respond to our fears differently.

Why she cares isn't within your control. That's her feeling, and she is entitled to it. The only change is that she's articulating it more clearly, perhaps because she believes you're ready to hear it, or perhaps because she believes you need to hear it. Either way, it isn't the reality that has changed--just your awareness of it.

I don't think I'd characterize it as a "honeymoon" period with an expected end. That implies it isn't genuine. Sure, there will be times when the relationship feels less blissful and more ambiguous. But that's transient and doesn't speak to the existence of the caring underneath.