Gojo never believed in reincarnation, he never believed that he'd be back. So, to see Geto's expression to that question made him realize, he wanted to be with Geto.

In every form that they would take. In every life that they could have together. Gojo wanted it.

Because even Gojo could not escape fate. In the end, Gojo wasn't the only one with a curse in his name.

Geto was bound to him, as he was bound to Geto.

"I hope we meet in our next lifetime."