Why are girls so complicated ?

Feel so depressed this girl i really like ive asked out a few times but things havent gone to plan if you know what i mean and a few days ago i kissed her and on msn that night we were playing "truth" and i said to her did u like my kiss? and she replied and said "i didnt expect it but somtimes the best things come unexpected" and now after that i thought yeah were goin somwere but yesterday she was drunk and this boy kissed her and it has absolutely traumatized me and i dont know what to do? whys she doing this ? do you think it was because she was drunk? FML i couldnt sleep last night properly honestly.. and when i do try and ignore her at school or online she keeps cummin back and keeps starting convo's and its not helpin me forget about her and that kiss i gave her just made things worse.. shes alwasy the one to start convo's i never try to talk to her anymore.. and do you think that kiss ment anything?