Left Out

I hosted a sleepover and two of my friends (let's call them Serena and Rylee) I had invited didn't really know much about each other but we all hung out and they got along pretty well. My Halloween plans were to go out with Serena and another friend "Kelli" but when I texted to confirm it Kelli said she's actually going with another friend and Serena said she's is going with Rylee... So both of my friends have become besties and have completely forgotten about me. If I didn't ask Serena about it or plans she never would have told me :((  And they obviously don't want me there because they haven't invited me ://