What do you do when your ex-boyfriend says it won't work between you two because you were both too obsessive and didn't give each other space?

If he doesn't want a relationship, then it would be unwise to try to drag him back into one. You don't want to be the only person giving and working hard to keep it together. It is just too taxing and you will wear yourself out emotionally. Let this one go. You need a better match. I am going through something similar. What I have learned is that you set up times when you are to be alone or out doing something with friends. That way you have alone time, to think and when you are together maybe do something productive, so it seems as though you are getting things done as well and then it won't come down to being obbsesive, but constructive. Spending time away is hard, but can ultimatley make a relationship stronger. Make sure the comunication through this process stays mature and understanding. Loosing that can cost you the relationship. And that hurts more after you put so much effort into it.