While there exist an exponentially-increasing and eternally-increasing number of realities based upon every conceivable choice you can make in any moment, your 3-D based consciousness can only experience one of them linearly at a time. The rest only exist as potentials.

It is analogous to having a infinitely-large library full of books. All the stories, information, facts etc. you could ever want all exist in a book somewhere in that library. But you can only read one book linearly at a time (in a 3D-style reality). (See How is it possible for me to be the creator of the greater context of my life?)

In every moment of Planck Time, a completely new reality is generated but your habits of focus ensure that each reality stays fairly consistent with the last one. So while there is the potential to completely change your entire Universe in the next moment of Planck Time, this doesn't happen in practice.

That's because what this 3-D focused reality gives you is a stable platform of singular focus. You wouldn't be focused here if you wanted to experience multiple simultaneous realities with everything manifesting immediately because all of that already exists in higher dimensions/densities, and the parts of you that reside there can already do that.

Multiple points of focus and instant manifesting is old news...boring stuff :) The fun, instead, comes from limitation...

There is value in being limited in focus.

So, coming to your question, it is those habits of focus that you have set up for yourself that dictate the nature of the limitations you are playing with.

If another being doesn't have the vibrational flexibility within themselves to be a vibrational match to your current habits of focus, they appear to vanish from your 3-D style reality (because everything in this Universe is attraction-based only)...and if there is resistance to them going, they can clatter out of it instead.

So that's why when you change your habits of focus (i.e. your vibrational setpoints on various subjects), the people around you change how they behave in response to them, if they can still match up to you, or else disappear...i.e. you drift away from old friends/relationships and new ones slide into place.

I think that clattering occurs when it is the path of least resistance.

Say that you are having a troublesome relationship with your boss, and you do work on your thoughts and beliefs in order to improve the situation. According to LOA experts, one of two things can happen: either your boss's behaviour changes towards you, or he or she gets phased out of your universe. I think that for the former to happen, it would take a much more radical shifts of belief on your part. Instead of just neutralising your feelings towards your boss, you'd actually have to shift to a vibration where you would have positive interactions with your boss.

I do believe in infinite universes, but sometimes it's easier to change your vibration in order to move to a parallel universe where a person no longer affects your life, or matches your vibration, rather than changing your vibration to the extent where your relationship with a person changes in a radical way.

However, it does happen. I've heard many accounts of people working with the LOA to completely change their relationships with certain people.

@Liam, I see what you're saying. Why not a universe where experiences of the other person add up to no resistance to what you want, since it's all infinite possibility?

This reminds me of the Abraham-Hicks Q&A our @Satori posted recently, in which the questioner asked Why can’t I just think my crummy thoughts and feel my crummy feelings and have everything just the way I want it?

Abraham said, "We love how ornery you are." LOL!

It has to do with the limitations you agreed to in deciding to live this life, as well as the free will and soul's purpose of the other person.

Abraham said, "If you had the capability of universal consciousness and awareness you would have the ability to change the rules of the game any way you would like, do you see? But as universal consciousness you do not find yourself focused in a human body. As a human, you simply don’t have enough awareness to change the fundamental, universal, agreed upon rules of the game. The laws of the universe are woven into the fabric of ALL existence, everywhere."

Such a parallel universe does exist, but as @Stingray said, as a potentiality. In order for it to become a reality for you, I think it would come down to the other person's free will to match yours vibrationally. For your own reality, you can't actually change that person, but you can bring to your experience one who's vibration does match.

When we are talking about expansion, it can be hard to imagine why one wouldn't want to come along for the ride, but I think it must be that we all grow at our own pace, and to fulfill our own soul's purpose.

It may also be that your own higher self has a purpose of his own in this situation.

:)