hmmm... she wont go out if it's a tad cold/wet/windy etc... she get's mad easily, and now refuses to have sex. hmm.... cut your losses?
yeahh i know that sounds mean but I had an ex that was JUST like that and man do I regret wasting my time. It just got worse. Now I'm not saying it will for you but I rarely see those things get better...at least not for me or any of my friends.

My gf now kicks all forms of ass, BUT I'm having the same prob as you...we've been dating almost 4 years and I'm lucky if it happens once a month now. Who knows what the prob is. Soooo I just take care of myself, that way it doesn't seem like im trying to get it all the time, and well if she wants it then it look slike shes going to wait like I have