Whats up with girls not making any sense?

Alright so basically, I have some questions surrounding the topic of girls. If a girl laughs at everything I say and she tells me to text her and I do, then she stops texting me randomly. What is up with that? Also, if a girl always talks to me in person and hella flirts with me in person, but she doesnt text me back, what is up with that? Thanks breh