He's having a party and did not invite me. Why? please help

We hung out all week everyday. For around 5 hours. On Facebook he put as his status "having a party wooot" And I put "with out me?" and he sent me a text saying "sorry"

i don't wanna ask him b.c it'd be annoying and clingy. Tho curious.I think he's into some chick idk. on Friday he kept trying to get me to stay , like saying "you should meet my friend you should stay longer." and I couldn't so I left.

I'm confused. why wouldn't you invite a chick to your party your friends with?