必ずしも~ない (not necessarily)

The end doesn't necessarily justify the means.

Fame isn't necessarily a byproduct of success.

Dreams don't always come true.

Conservatives aren't necessarily reactionaries.

It's not always easy to tell a good book from a bad one.

You don't necessarily have to go to the airport to reconfirm your airplane reservation.

Theory and practice don't always match.

Theory doesn't necessarily match practice.