If there's no good theological way to explain that Jesus told a little fib because He had to or because He was human, then that still leaves us with the question of what we're supposed to do with this story in John where Jesus appears to tell a little fib. Where the God of truth appears to lie. He said He wasn't going to Jerusalem, but as soon as everyone else left, He did go.
Maybe, we think to ourselves, Jesus didn't actually tell a lie. Maybe what looks like a lie is actually our inability to understand what He actually said. After all, we are finite human beings and our understanding is limited; we openly confess this. We know that we don't understand everything about God. Maybe this is one of those things we just don't understand because we don't have the ability to understand it.
Now, there are two ways that we are most likely to approach this line of reasoning. But neither of these is theologically satisfying, either. In fact, they, too, create more problems for us than they solve.
First, we might say that Jesus was speaking cryptically, that we weren't supposed to understand what He was saying here. We know He did this sometimes. The Bible tells us that He did it and in fact, Jesus Himself tells us that He did it. He spoke in parables quite often, using stories to illustrate points, and even His disciples had trouble understanding what He meant. Part of the Gospel story is Jesus explaining to the disciples later what they didn't understand when He said it. So maybe when He said He wasn't going to Jerusalem, it was one of those things that He'd have to explain later and John just doesn't give us the explanation.
That would certainly explain things. Except...it doesn't. Because even though we know that Jesus spoke in parables, we also know that most of the time, He didn't. And there is no evidence at all that this little scene in John is a parable; it seems very clearly to be a historical recollection - His brothers asked, Jesus answered, then Jesus acted. That's not a parable.
We know, though, that sometimes, Jesus spoke plainly and His disciples still didn't understand. But again, that's not a satisfying explanation, either. Every time this happened, it was about Jesus's upcoming crucifixion and glorification or about the Kingdom of God. It was never about an action that He was going to undertake in His physical life. So it's a hard stretch to try to say that this is the one and only time this ever happened. It's just unlikely.
Even if these lines of thinking were not intellectually dishonest to the Scriptures, they would create theological problems for us. How are we supposed to worship a God whose Word we are not supposed to understand? How are we supposed to love a God who speaks to us in words we aren't supposed to comprehend? That doesn't make any sense.
Second, if we decide that Jesus wasn't speaking cryptically, then we might say that there's a language barrier anyway. We don't understand fully what the Greek meant. Maybe we aren't translating it correctly. Maybe we're missing something about the nuance of the language, something maybe as simple as the words "with you." Jesus didn't say, "I'm not going to Jerusalem;" He said, "I'm not going to Jerusalem with you" and we just lost it in translation. Yes, that must be it.
And we know that sometimes, this is true. Scholars have spent years trying to fill in the gaps of the Scriptures, especially where only partial manuscripts have been found or degraded manuscripts or whatever. Sometimes, they're right. Sometimes, you can tell they are just trying to fit things into a nice box. Sometimes, they'll even tell you that they found evidence that some ancient scribe was trying too hard to fit things into a nice box, so current scholars don't believe what they read. They think it's not "original" and that something else was meant or said.
But again, this creates more theological difficulty than it solves, and for much the same reason. How are we supposed to come to know our God if His Word is distorted? How are we supposed to trust what we think we know about Him if we've had to fill in the blanks ourselves? What good is the Gospel witness if there is any suggestion at all that even one word of it doesn't mean what it appears to mean, if we are convinced that there's such a barrier of language between us and the Gospel that we cannot grasp it? We can't build a faith on this. Not a good one, anyway.
So neither is it enough to simply say about this passage that our finite nature and limited understanding somehow keeps us from comprehending what's really going on here.