Why is my friend like this?

Okay so my friend Julie and my other friend Jess is planning on going to the mall tomorrow. I asked if i could come and Jess and she said she doesnt mind and I asked Julie and she didnt even reply to my text. Now that their at the mall right now I asked Jess what the deal was and she told me Julie didnt really say anything about me wanting to come. I know for a fact that Julie doesnt want me to hang out with them for some reason. Julie also knows I am a better friend with Jess than she is with Jess. But me and Julie are better friends than her and Jess. I know this is confusing but Julie is really pissing me off. She lost one friend, and she might be losing me. She's being really selfish and rude and shes ignoring my texts. Is she trying to make me jealous or something?