The one who Elon Musk either fucked or they wanted to fuck with Segey. Who knows (that isn't a question).
Discussion
Or maybe Sergey used it as an excuse to move on. This is much more interesting than saving the planet, of course.
To be fair, there are, of course, many more possible scenarios when i go on a rant like this. I mean, maybe the baby momma was over the relationship and was setting up her politics future. Who knows.