Well getting woman does not seem to be a problem... but holding on to them does! Maybe I'm still not over my long term girlfriend to have another relationship that's why they keep failing. Or maybe the fact the last one was 18 and I'm 26 is why. Or the one before was just crazy. Either way I'm starting to get a complex!

More than likely you are going for immature girls who have no interest in really being in a LTR. Try a different type girl to get interested in. Maybe even your age or older.

If you're looking for a serious relationship, forget what your GF has and think every woman you meet as unique. Also, avoid dating too many women at the same time. Just pick someone you think you really see yourslef as your serious partner. Why? Because you will not be able to give focus making each one of them think your just playing around their emotionsmaking them to dump you. Take time to get to know each women and don't just date and dump and dump and dump too. Besides, when you convinced a woman to date, that doesn't mean the work must stop.

First four people you dated in 4 months are not "x"s, they are merely people you dated some. And if you are single and coming off a long relationship, you should consider dating several ladies even at the same time and see if there is one that has similar interest.
And of course a 18 year old to remind you that you are getting old never hurts either. After my wife passed and I did my proper mourning, when I started dating, I dated several various girls, finding out about them, they are not really a X unless you were into a serous relationship for months at least in my book, they are just friends for the first few months of dating normally. I am sure it is a play on words but someone you dated for a few weeks can't really have gotten that serious unless one was jumping in too fast.

You have to find someone that's wants the same things as you. Look for someone on your level and if they don't want the same as you then leave them alone and neve settle. There's someone for you, you just been meeting the wrong females. I'ld suggest writing down what you want in a relationship/female, and don't want. As you meet females talk and find out about them and see if their goals match your. Also, look at the females from your past and write what you saw in them and maybe you can see for yourself where you went wrong.

Either way I'm starting to get a complex!

Its only dating, having a good time no strings attached. If your looking for another relationship to replace the last one, STOP!!

Date for the fun and good times. No other expectations, just fun, and you what worry about complexes.

You get a complex from high expectations that are not met. Lose those high expectations.

Did I mention its for fun only??

Now enjoy yourself, even if they are flakes, and you never date them again.