How else to say "We've come to a parting of the ways"?

Very considerate of you. I usually get ghosted or worse.

I recommend being In a neutral safe location, and give her a chance to change her ways.

Every way would hurt. I don’t know how to say it otherwise.

I would try saying that, “I don’t want to hurt you, but we need to go our own ways.”

If you can figure away to break up with out hurting someone then come back and tell us?

Since it’s a friendship and not a romance, so therefore there’s no expectation for a regular meeting up, it’s not possible to just severely curtail seeing her, instead of meeting her and having to explain things? Since you will see her in group settings (presumably meetings and/or parties/celebrations), in the meantime, can’t you just make yourself “always busy, too busy for coffee or lunch?”

Reasonable Q, @jca2. But we’ve had quite a close friendship over a number of years and been each other’s confidantes during that time. I can’t just withdraw and go silent without some word. She can see I’ve cooled toward her, and she’s asking.

Thanks, @RedDeerGuy1, for your kind thoughts.