He is showing behavior characterized by 'chuunibyou'.

I cannot forget that specific date.

His young and tender heart was very sensitive to new experiences.

His music conveys a sense of youth and tenderness, healing the heart.

Your actions are a clear case of copyright infringement.

He made a deep apology.

I deeply apologized to him.

This project is still in its infancy.

He was lost in faltering worry.

He was faltering in worry thinking about the future.