Which lines from robert frost’s "the road not taken” most convey a tone of regret?

Pardon me. to answer questions like this, we would have needed more information. for starters, two sentences from the excerpt that came with the question.

Ialways thought that he thought it wasn’t fair because he thinks that people should be able to experience things and think outside of the box, or see color and add brightness and happiness to their lives but idk.

Iam confused at the end of the day i can’t always get the stuff right i need more then this so i can’t u