If you told your boyfriend you wanted space, then later regretted your words, your chances of winning him back depend on how successfully you can convince him that you really care about rekindling your relationship. Your success also depends on how much your boyfriend loves you and if he was committed to the relationship. Further, it depends on whether you did something like this to him in the past -- and if your boyfriend is the forgiving type. However, if you put a lot of thought into what you say and do to win him back, you might be surprised at your success.
Think about why you asked for space. Your boyfriend will need to know the reason before he can decide whether or not you are sincere in your desire to reunite. Perhaps you were going through a stressful period due to your work or family. It helps to let your boyfriend know that your request for space was due to your personal problems and not a criticism of him.
Learn from your mistake. If you acted impulsively in the past and later regret your actions, resolve to think more carefully before you say or do something you might regret. Reassure your boyfriend that if he gives you another chance, you won't repeat history. Keep in mind that regret can be beneficial because it makes people consider future decisions more carefully, notes clinical psychologist, Melanie Greenberg in the Psychology Today article, "The Psychology of Regret."
Apologize profusely and tell him that you love him. However, be careful not to harass him. You need to strike the right balance between begging for forgiveness and respecting his need to be alone. Tell him honestly why you changed your mind and how much you regret it. Let him know that you understand why he's hurt.
Give your boyfriend some time to consider your request to get back together. He'll need to be convinced that if you get back together, you'll be more committed to the relationship. He might be reluctant to risk additional hurt, so you need to rebuild his trust in you and in your future relationship together.
Don't pin all your hopes on your boyfriend forgiving you. If he's the sensitive type and was badly hurt by your request for space, he might find it impossible to forgive and forget. Should this happen, you simply need to give up hope of restoring the relationship, according to author and radio personality, Margaret Ruth in a Huffington Post article. You're likely to find peace of mind and be happier if you accept the reality that the relationship might be over.