hello ,i have read your whole problem .here is my suggestion :_
1 first thing you understand majority of boys do flirt with another girl no matter they are single or married but not all ,so you have to find out how
he reacts when you are with him and as well as not .in this way you can know about his inner side personality about other girls.
2 second thing you must understand you are his girlfriend so you have no need to afraid and feel bad because you are not doing any mistake but you are behaving like a slave and also you are behaving like a girl who is dependent on his boyfriend .so whatever he said to you or scolded you then this is your authority to ask them clearly in lonely place not in front of every friends when conversation is going on. you say to him see " see asad i am feeling bad due these following reasons i want to know answer ." he will give you your question's answer if you feel satisfy with his answer and you think his answer is logical and genuine then you will feel good another vise bad.
3 third thing you must know in India , i live in india also i have seen only in my whole life 2 or 3 cases of marriage those who are boyfriend and girlfriend relation,but 97 present boys don't do marriage with there girlfriend. they do sex and after some time break up and find another girl for to make her girlfriend or do marry with another girl. why because they want to take another taste , it looks creepy but it is true. so if you think you are serious about him so much then you must remember all these things another vise you will become misuse,.
4 thing is that there is no need to ask your personal problem solution to everyone or anywhere try to solve out self ask to your mind and your heart and search on internet .if your mind ,heart give you advise that means both are right no matter what another people say you are in love you are in a relationship with a boyfriend who is responsible to make you happy and feel good and do nice behavior .
5 my last opinion is that i have read your whole problem and i feel you are very innocent because your boyfriend misbehave you and you are asking to people why he does misbehave , does am i doing something wrong? so he is your boyfriend but he is doing misuse of you and he will be not honest for you until you catch him red handed your boyfriend red handed with another girl , i know that right now you will not trust me because your mind and heart will not accpect this , but in future your relationship will break and he will leave you not you.so better is do cautions don't do sex before marriage with your boyfriend ,and respect yourself not sympathy and don't become confused person without any reason another vise you will become mentally ill.
6 don't take him so much seriously because you are doing your best to understand him but he is not ,he is not giving you respect and you are giving him respect if you will continue on this then you will become mentally sick ,or if you do misbehave with him in his response then you will think you have done wrong thing to him so better is become serious try to solve out problem with conversation ,if it doesn't solve it means you are with wrong guy .
i think he is not a good boy and he is not serious about you (you will find out in future i am damn sure) .i hope these soltons will make and teach you to take your decisions own and respect yourself and recoznize a person by using heart and mind (first you think then think about another people) and last dont behave like a child and inoocent behaviour and be strong and ask and raise your voice if anyone make you feel bad (if evry time you will be in silient mode people will think you are week and your peronaility will become scary and your opinion always be dependt on others and these whol things will male your life hell )
i wish and i hope and i believe that these solutions will help you ,god bess you , bye and have a nice day.:) keep smiling see yea