WOW so my cousin was trying to play me?

My distant cousin that I havent hung out with in years asked me to go out with her this weekend for my bday. I told her ok and we met up at her house, I was with my mom and my god son's mother. When we got there she was acting really WEIRD like she didnt even want us there..it was very uncomfortable, but she kept saying how she was happy to see us, etc, etc...It was almost 11pm and still wasnt dressed, showered or anything like that so I told her we would come back once she was dressed, well it turned out that she was actually wanting me to go alone and not with my mom and friend so I can hang out with some girl that still has a 10yr grudge against me..It was like she was wanting me to feel uncomfortable or something..WTH!! Im glad I listened to my instincts when I duffed her A$$ that *****!! Why do ppl act this way..I just dont get it.