What kind of relationship u both share is very important.. if u r seeing her as a long term companion u r bound to become possessive n insecure about her.. so get things clear by talking to her.. like whether she also have the same feelings the way you have towards her.. otherwise u will fall for her everytime n expect d same from her n end up getting frustrated. Learn to be more flexible n not rigid when you expect something from a person.. Ex : How dares she lies to me knowing that I don't like lying n she should not lie to me -  a rigid statement I expect her not to lie to me but there is no guarantee that she won't - flexibility in thinking ( since she has her own choice of not telling u everything or may be she don't want u to get possessive)