YOU have a problem not her. Let's get that straight right from the start. Trust issues usually stem from past experiences where our trust has been betrayed. I would suggestion looking at your own past and see the trust issue as a past experience and work through that before attempting to work through present issues. Usually knowing where we had an experience and viewing it in context of past will lessen the impact of effects on current problems.

"I want to trust her" is the mistake. If you don't trust her, you don't trust her. Wanting to be some other way is a little odd... what would that even mean? Well, clearly, it means you have some idea that you SHOULD trust her -- that if you were a good person, or something like that, then you would trust her. Or maybe you feel like somehow you're weak because you don't trust her. In any case, the resolution is to become aware of exactly what is going on inside your own head and heart about this, and stop trying to fix it. If you do that well, you'll probably find several "layers" of beliefs about yourself and her, and about relationships... this will include ideals about how relationships should be, ideas about the type of person you are (mostly based in your past experiences involving love), ideas about how women are and how she is, and so forth. When you can SEE all of that stuff, and just stop trying to fix it all but let it just be there, the next thing to do is to notice that it's all from the past -- it's a bunch of automated thoughts that (for the most part) you didn't make up -- you picked those things up from the culture and your exposure to other people. The purpose of this whole exercise is to get a little bit of "blank canvas" in your relationship: an opening, some freedom, a recognition that maybe you don't really know yourself or her all that well, coupled with a curiosity to discover and find out what is ACTUALLY available in your relationship, rather than being buried by all of your concepts and images from the past. And in that blank canvas, real trust can show up if you communicate and if the conditions for trust are appropriate in your relationship with her. But first you gotta break the stranglehold of the past, which is what prevents you from seeing clearly.

I know exactly how you feel, I have the same problem, I am completely inlove with my boyfriend, and I know he's the one, but because of my past, I find it hard to trust him even though he hasnt done anything. I put reasons in my head that make me not trust him like when he says he has to work late, or go do something i think "could he be with someone else?" And the only thing I found I can do is to tell yourself, and remember that she loves you, and she wouldnt ever want to hurt you (this is if you think she really does care) Tell yourself that you are being insecure, and try to catch your train of thought right when you start thinking it, and ignore it (i know this is hard, but eventually it will help) And at first it feels like your lying to yourself, but after a while, it will slowly diminish, and if she still hasn't given u a reason not to trust her, maybe you'll be able to. If all else fails, hire a private investigator, when u think shes definatly cheating, and find out the truth. If she is, then u know, if she isnt, it will probably help you realize that you're being rediculous, and maybe you can learn to trust again