My sister had a sleepover the other night and invited her friend Alli and we flirted all night. She has a boyfriend for 1 year now but she is thinking about taking a break from him and we talked about it and I told her I thought she should because he has cheated on her 4 times now. She is the most beautiful, Intelligent, and funny girl I've ever met. She has the most amazing smile in the world I never understood why people said that until I saw her smile. I really like her I might even be in love with her and I think she likes me too. What should I do?