Two-way trip. Who started it?

Simon Beauvoir. "Going in both directions" comes from Simon Beauvoir's "Overseas Love Letter" which came from 1947. The book says: I am eager to meet you, but please remember that I won't open my mouth to see you. It's not because I'm proud, you know I have no pride in front of you, but because it makes sense for us to meet only when you want to see me, too. So the word "two-way rush" began to be widely used and popular.