How legit is the "I need to work on myself" break-up excuse?

My ex broke up with me a week before we were suppose to move in together and he gave me that excuse... that he isn't ready for a relationship, thought he was, but isn't and now has to work and focus on himself... btw... anyone think he'll come back?
How legit is the "I need to work on myself" break-up excuse?
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