Cruz’s fault. I think it would be wonderful for trump to run 3rd party (even write in) if trump is screwed going into Cleveland with over 1,000 delegates to Cruz’s 515. Alaska had a write in everyone thought would fail. That proves it can work and his name is easy to spell. Lol.
The way the math works, if Trump had 1,000 going into the convention then Cruz would have 1,004 if you assume Kasich picks up another 25 or so. At this point, Trump and Cruz have about 2,000 delegates to split among them, not counting the 113 uncommitted which are likely to break mostly for Cruz (330 are already taken by Kasich, Rubio and others). So Trump will have to get around 1,150-1,200 to put Cruz back with ~950-900 which ought to be a big enough lead to swing the convention Trump's way. Doable if he steps up his delegate selection game. To get to that situation, Trump & Cruz would essentially need to split the delegates in the remaining primaries - pretty plausible.