My boyfriend has trust issues :( Help?

I love my boyfriend so much ... but he has really bad trust issues and i fear that they may drive us appart ! wer in a long distance relationship at the moment but within the next month we should be together, if all goes well. I no being in a long distance relationhip doesnt help but wenever trust is the topic i tell him everytime that i dont want or need anyone else. Sometimes it dries our conversation up and i just wish he could trust me! He knows he has trust issues due to previous relationships but it really hurts that he doesnt trust the one person in his life that will not hurt him ! When we are together i ***** b happier and it feels like a part of me is missin when im not with him. I just want to gain his trust in whichever way i can, i just want some advice and what to do what to say to him ? because its really bringing me down.