I read a good article decades ago that address some of this problem from Calvinists. The ending of the article, I think really gets at what your talking about.
FJ: God predestines according to foreknowledge and His eternal purposes. Part of His eternal purpose is that Man would love Him of his own free will, and not by any necessity. Those that respond to God's grace are foreknown and predestined to be heirs of Salvation, according to God's eternal purposes. Those that reject God's grace, are foreknown, and are accordingly appointed unto damnation. Those that reject God's grace are therefore, justly condemned.
For some reason, you think that this cooperation would mean that man merits his salvation. But if some ransomed prisoners choose to stay with their captors, while other choose to be free, no one would say that those thus freed had merited their release.
Dialogue on Free Will & Determinism