Do you think maybe they come from fear and denial? My boyfriend and I used together and cleaned up together. The first time we quit, he started using again behind my back. I was so broken-hearted because he had lied to me. I thought that I could never forgive, instead I started using again too. Now that I look back, I realize the reason he was dishonest with me was because 1) he was afraid I would be mad & not forgive him and 2) because he wanted to protect me and keep me from using again. We both quit again on the 1st of December, and now I realize that even though I did forgive, I haven't forgetten. I am suspicious of him all the time now, and am worried that he is using behind my back =( The thing is, I really don't think that he is (honestly), but no matter how hard I try, I can't get it out of my mind. I don't think that this really answers the question you asked, but I understand the feelings that caused you to ask it. It is so hard when you love someone more than anything, but yet you can't or don't trust them. Nearly drives you insane.
"Sed fugit interea, fugit irreparabile tempus" - Virgil