I am a Cruz supporter. Cruz has been working to close the nomination deal. Either he does, or he doesn't. That's his problem.
It isn't "unfair" if he doesn't manage it.
Same with Trump, Kasich or anyone else. Everyone knew how things worked going in, or should have. Everyone certainly had time to find out how things worked over the last year. There's nothing unfair going on - this is how the process works. It's not news. Whichever candidate gets nominated is the one who is able to close the nomination deal.
You can complain about the GOP backroom establishment all you want. That won't change the facts. Everyone knew the facts going in. This is life. Conservatives don't whine about how badly life treats them, or how things are unfair. The world doesn't owe us anything, nor does the process owe any of the candidates anything. The process is the process; it is a well-known process.
That is all.