boyfriend can't trust me, why not?

My boyfriend doesn't seem he can trust me. he thinks i am sleeping and/or messing around with out guys. he says he can hear it in my voice. The thing is i am NOT messing around or sleeping with anyone else. I use to engage in risky behaviors such as that but, that is how he meet me. Why can't he just believe what i tell him. I never cheated on past boyfriends just went out with different guys while i didn't have one. Why did he ask me to be his girlfriend if he knew that he couldn't trust me because of my past? anyone have an advice to help change his mind about trusting me?

hey jenny how are you? well is there anything that makes him think this at all? so you like him alot and he must like you alot but there has to be a mutual agreement between the two of you. you cant have distrust in this relationship or it will go all down the drain. and you probably dont want that jen. well if he is think this way, why? what is it giving him these thoughts? you need to go and search what it might be that is bothering him. because if you let this keep going the way it is then going to be a harder fight when things blow up to the extreme. well i hope you can make him realize that you arent doing these things and you do love him. well take care and i hope things go well. later.

The thing is, Jen, the guilty ones commonly accuse others of being guilty of what the're doing, example; a liar never believes anyone and a thief never trusts anyone alone with his or her stuff. try to work through this with him and ask him if he is guilty of the accusations he tries to pin on you. if he can't change then you need not try to change for him. as your boyfriend it is to be expected of him to trust you, stand by you, and not try to use your past to manipulate your guilt level.