Perelandra and the Will of God

I'm currently rereading Lewis' space trilogy (Out of the Silent Planet, Perelandra, That Hideous Strength) because I haven't read them since fifth grade, when I was looking for another Narnia and this wasn't it.  I'm liking the books a lot better this time around.  Perelandra is still mostly just the characters sitting around and talking, but I understand the theological implications now that I didn't understand when I was 10.  At one point when the Lady (the Venusian Eve) is being tempted to sin for the first time by Weston (a Terran who is under the control of Satan), the Lady says of God:

"To walk out of His will is to walk into nowhere."

I'm having a bit of trouble deciding exactly what Lewis meant by this, since I can see three possible meanings (and there may be more):

1. Lewis meant that no path is actually outside of the will of God, because everything that happens is either performed or permitted by God
2. Lewis meant that walking away from the will of God in one's life is like walking into a black pit of nothingness because without God everything is nothing
3. Lewis meant that both of the above statements are true, because God allows man to choose, but if man chooses to reject God, then he also chooses the nothing over the something

I'm not familiar enough with Lewis' theological leanings to know if he agreed or disagreed with any of the three options, so some research is probably in my future.  This is probably just a minor semantic query and I'm probably reading way too much into one sentence, but I'm really curious to know what Lewis meant.