I was at a friends birthday party the other week and i met this really nice guy, when we got into the club we really got talking and hit it off and when i wasnt listening he asked my friend if i was single, (which i am). Later on he then i asked for my number and asked if we would like to go out and we ended up kissing and having a really good night together, it was really nice to meet a guy who doesnt drink as well. And when we got back to the house we both curled up on the sofa together.

That's excellent, a perfect place to meet and a perfect end to an evening, curled up on the sofa but no sex. 

He also invited me out the next day but i was working.

He text me the next day and asked if i had a good night and we both arranged to maybe go out that weekend but i found out i was working that weekend he said that if i didnt want to go out then that was fine and he then seemed a little off!

Two strikes and your out.  You know you have a genuine reason for missing both date invitations, but he doesn't know that.  Guys are used to women pissing them off and dithering, he will have experienced this in the past.  He will let a woman off for missing the chance of one date (though one date will frustrate him too) but if you can't go for two in the row, then several thoughts run through his head:

• She's playing silly games and is playing hard to get, men hate that!
  
• She's saying she's not interested anymore.
• She's having second thoughts about us meeting up, men don't find dithering attractive!
  
• She's saying she's not that interested, in which case, he's not that interested anymore, there's plenty of other women he can turn his attention to.
  
• I blew it by being too hot with her and I should have been cool with her.
• I'm lousy with women and have obviously said or done something wrong, so I just give up trying anymore, women are impossible.
• She's found someone else.

You may think, it's completely unfair to come to any of these conclusions.  But you've got to remember that women piss men about like this all the time.  He doesn't want to have to mind read a woman to work out what she's saying or what games she's playing, he just wants a woman that likes him as much as he likes her.

Im really annoyed cause he is such a nice guy and i dont understand why he was so forward that night and not now.

i would be really greatfull of any advice as i feel their is something about this guy and he is too nice to forget about.

I'm being very serious now.  The ball is in your court.  You are the one that refused to go out with him because you were too busy on two occasions, I know you have a genuine excuse, he doesn't know that.  He thinks you are not interested or not interested enough or even playing games.  He's given up on you and is unlikely to ask again, because he would feel lame doing that.   His mind will be moving on, he will be thinking I need to find another woman, because she's not interested.  So he will be persuading himself you weren't right for him anyway and assessing his other female options.

What you need to do is act quickly and send him a message saying, "I'm available this day and this day to meet up".  He probably won't be too impressed still but at least you are saying to him you are interested and as I say the ball is firmly in your court, because of what has happened, there's little chance of him making the next move unless you clearly say to him, I want to meet up and I'm available these days.