Deals Fall Through
Birds fly, fish swim, and deals fall through.
Death, taxes, and deals falling through.
Use whatever acronym you want. They all apply.
I've been working in sales long enough to know that a deal is not closed until it is closed. No matter how likely you think that deal will close there is a good chance it doesn't.
I've had deals that I swore on my life would have closed and they didn't. It's just the way it goes.
One good question to ask when you think you're close to finalizing a deal is, "If this deal were to not happen, what would be the reason?" It will help you understand what hesitations the other side has.
But alas, whenever you are in a deal-making environment, just know that often deals fall through.