Because he have to choose only one road between two road and he choosed 2nd road that's why he feel sorry for 1st road

Reasons for feeling sorry:
- Regret for not being able to travel both paths: The poet feels sorry because he knows that he cannot take both paths at the same time. He wishes he could explore both options before making a decision.
- Fear of missing out: The poet is worried that he might miss out on something significant by choosing one path over the other. This fear adds to his feeling of regret.
- Uncertainty about the chosen path: The poet is unsure about the consequences of choosing one path over the other. This uncertainty makes him feel sorry for not being able to predict the future.
- Wistfulness for the road not taken: The poet feels a sense of longing for the path he did not choose. He wonders about the possibilities and experiences that could have awaited him if he had taken the other road.
- Realization of the finality of choice: The poet understands that once a choice is made, there is no turning back. This realization makes him feel sorry for the roads not taken and the opportunities that may have been lost.
In conclusion, the poet feels sorry because of the regret, fear, uncertainty, wistfulness, and finality associated with making a choice between two paths. These emotions highlight the complexity of decision-making and the impact of choices on one's life.