The absence of observing someone or some object to date suggests that multiverse can not be observed or can not exist, because if it was possible to observe or if it did exist we would have seen some evidence of it by now.

In an infinite universe, there should be constant evidence of multiverse apparent.

In an infinite universe, there are an infinite number of variation of universes with properties implying any given of event happen 0, once, rarely or often.

That's the problem with the infinite universes theory. You can pretty much make up whatever you want, it answers to any question.