てからというもの

〜てからというもの is used when one event in the past becomes a clear turning point, and because of that event, something changes and stays changed until now.

This grammar does not simply mean “since that time.”
It strongly emphasizes change + continuation.

The speaker looks back at the past and explains that:

• something important happened, and

• after that, their thinking, feelings, habits, or lifestyle changed, and

• that change is still continuing today.

Because of this meaning, the expression often sounds:

• reflective

• personal

• emotional

• serious or thoughtful

It is commonly used in written Japanese, essays, explanations, and formal speech.

Key Notes

• Focus is NOT time, but lasting change

• Stronger and more emotional than 〜て以来

• ❌ Not used for simple time duration

• ❌ Not used for short-term or temporary situations