〜ずじまい

Meaning

Indicates that, despite intending to do something, one ended up never doing it. Stated with the lingering regret of not having carried it out.

Examples

忙しくて、結局その映画は見ずじまいだった。 I was so busy that I ended up never seeing that movie.
お礼を言おうと思いながら、言えずじまいになってしまった。 I meant to say thank you, but ended up never being able to.