There are a few things that I feel aren't emphasized enough in LoA books or at least not in this forum:

You are god

When you really understand that statement, things will speed up for you and I can tell you that from experience. It makes a world of a difference, if you identify yourself with your body or if you take a step back and realise that you are god, infinite consciousness and therefore everything and everyone that exists. You are your whole world on some level. This knowing makes you infinitely powerful. You don't longer try to change your world. You just know that your consciousness is the only truth anyway and whatever thoughts and feelings you entertain in your consciousness will find expression in the reflection you call the outside world.

You have to be it

That statement isn't easy to understand in the beginning. It means you have to become an actor and you have to play the role of the new you, the you that has what you want to have. A good actor doesn't just play a role. He becomes the character. What thoughts would this character think? How would he feel? What would be important for him? Study your new role, think about it and then start to train yourself into it. Don't do it to manifest something. Do it, because it's interesting and fun and you can learn something from it.

Be it NOW

One of the mistakes I see the most here is seeing the relationship as not here, but with a little luck in the future. As long as you see it in the future, it will stay in the future. As long as you feel him/her to be your ex, he/she will be. Don't wait for your reality to change. You can wait your whole life for that to happen. YOU have to change first.