private matter

What she may be to me in the future is a private matter.

I'll have you know my writing is a private matter.

It was a private matter, and she had seen no need.

We are going to speak of a private matter alone.

Her love was still a private, personal matter at this point.

"This is a private matter between the girl and me."

For the most part, religion is a private matter here, not a political one.

Now we start to talk about private and personal matters.

Religion is a private matter and should not become an issue in any political campaign.

This is a private matter, not one of the public events for the trip.