“Our lives are back to front.” 6x01 - Day of the Moon
Every leap of faith the Doctor had to perform, little or big, River had to do as well. Every shock she got when he was not her Doctor –and overcame it-, he experienced when she was not his River. Every doubt, every half- confession, every step back, they both faced.
But never together.
They fall alone, cross galaxies and centuries before being in synch for a second, keep missing each other at the start, but their future/past counterparts are extending their hands to catch them. They are trapeze artists. They always fall without a rope or a harness, but they trust the other to show up just on time with a name on the lips like a net. Even if as they are taking a run-up, the other is nowhere to be seen. This requires trusting oneself as much as trusting the other. Trusting the other’s ability to palliate one’s mistake and oneself to choose wisely each gesture. And they trust their freedom of choice, in each situation. In a dance of equals, they are both clueless and omniscient about each other’s future.
The difference is that most of those steps in trust were passed by River in an afternoon in Berlin and, later, off-screen, at Luna University and in prison. And that while River had to dig her trust to the Doctor, removing years of brainwashing and biased information, the Doctor had to build it from scratches; before trusting River, he trusted his future self who would trust her –and be right to.
Back to front means she trusts him to be her eyes in the past, and he trust her to be his voice in the future.