にはなれなかった

couldn't become

→ に
phrase Rare #30,316
couldn't become Used after a noun or description to say someone could not become or be something. After 気, it can mean “couldn't bring oneself to.”
JA: 彼は医者にはなれなかった。
EN: He couldn't become a doctor.

経歴のために彼はその仕事を始めたのだが、好きにはなれなかった。

He took the job to build his career, but he didn't like it.

好きにはなれなかった。

I couldn't bring myself to like it.

彼はプライドが高かったので、その屈辱を無視する気にはなれなかった。

Because he was very proud, he couldn’t bring himself to ignore the humiliation.