I've been reading some of your posts and Phil and Al_phaD have made some salient points that you'd do well to follow. As for me I'm going to wade in on the happiness front.

Happiness is a choice

As much as the clothes you wear, your mood is a choice - so choose to be happy. Seriously when somebody says something you don't like ignore it or put yourself in their boots, just think nobody died, it's amazing where greeting things with a smile will get you. Don't get pissed off with things you essentially can't control and those that you can control do it positively. Yeah sometimes stuff happens that will hurt offend but its how you deal with it, choose to examine what happened/is happening and how you can make it positive. Lets examine your situations:

Your current girlfriend - She seems like a nice girl who's not for you. So tell her that "Honey, I love you but I'm not in love with you. We've been together this long and we're only working as friends". She'll be pissed but hey you'll never see her again or she'll be ok after a month. Then move out to your own place or a houseshare and don't run straight into a relationship, take some time to discover yourself without her influence.

This girl you fancy - As Phil said don't worry about her. The more you go out and attract women in the world, the more you'll understand that you can have a choice of girls and that there are far more fun and attractive girls that you yes you should be going out with and devoting yourself to one girl will stop you being the kick-ass social dude you need to be. You however may find that she'll come back round if it's meant to be.

As Phil aptly said - don't be outcome dependent i.e. dont give a shit. that's the difference between your friend the natural and yourself. He doesnt care if the girls like him or whether he gets their number, hence he does well because he wont be upset if he's turned down, so get out there, approach girls, find that they turn you down and you dont die! then carry on not dying and approaching girls. The only point I would disagree on Phil with is about being a cunt for a bit. Phil does know his stuff and it does work a beast but i would advocate an approach that is aligned with the guy you want to be.

As for PU material, I found the mystery method worked really well for opening and starting conversations when i got into PU and then I watched RSD blueprint decoded which blew me out of the water. These worked for me, but you might find you prefer a different style such as NLP etc.

That's just what i would do in your position - have fun...