If only you could drag yourself away from your work and responsibilities so you'd have something to contribute to a serious relationship. But alas and alack, you are so driven from within, so overcommitted, so darn serious, that it's really hard for you to loosen up enough to just relax and have a good time. There are always so many things weighing on you that you feel like you're wasting your time and effort if you're not actually accomplishing something.
Here's a thought: How about including 'relaxation' on your list of valuable activities! This one small change in perception could go a long way toward alleviating the problems that prevent you from successful relationships. No matter what, you're going to have to put aside your usual day-to-day concerns in order to relate happily with others. It won't be easy for you but once you've connected well a time or two, it becomes its own reward.