You can solve it in a few ways. First, analyse it. Find the cause. Why are you single? Do you stay at home when you should go out? By doing so, girls won't even know you exist. Or, are you too shy? If so, why are you shy? Try to dig to the root causes.
I have 3 at the moment, as to my knowledge only 1 gf at time always make you headache, and more than 1 mean that you are giving headache to them. So make 1 as a permanent and other as a time pass.
Truer words were never spoken... I've been in the position of having as many as 3 at the same time (they all knew about each other, in fact 2 of them fell for each other and me at the same time... and it's NOT all you think it's cracked up to be!! LOL) Just one for now is plenty, and we've been happily together for over 10 years.