Doubt starts within you. Reprogramming your mind, I think, is a really big deal in manifesting your desired results. Like instead of thinking like this for which in your case as since you came here out of your lover, “will he come back?”, start reprogramming your mind that “I know very well that he will come back”. And live your life as if he didn’t left you.
You could also ask some spirits to help remove those doubts. I suggest to start with Lucifer, as He could advise you some avenues to forget those and to start thinking about yourself more. 10/10 I worked with Him and He’ll give you a lot of options which are all beneficial to you.
PS
He’s my spirit guide and I greatly respect him! Hail Lucifer!