I don't know if my advice is particularly great but I hope it helps.

Trust is really important in any relationship (I'm sure you know this). Without trust, neither side ends up being happy, because she'll be eaten inside by jealousy whenever someone else so much as exists in your life, and you'll end up miserable because she's accusing you of something serious that you haven't even done.

This is something that you should point out to her. Talk to her, not when she's exhausted after a day or work or during the heat of an argument, but when she's calm and willing to listen to you. Explain to her that you're hurt by her accusations, because you would never cheat on this guy, and that you'd like to know why she would think that so that you can discuss whatever is wrong and solve it together. Don't lash out at her and don't point your finger. Maybe your girlfriend misinterpreted something or did, or maybe you have been distant for some (perfectly valid) reason and she thinks you're cheating. This is nobody's fault, so it's no use pinning the blame on her for not "getting it", because maybe it was a failure in communication both of you experienced. So just try to understand why she's saying this and work with her to solve the problem. Unless she's slowly becoming paranoid (which is unlikely but possible) or unless you're guilty, it can be worked through if the two of you try.

This is just my two cents but feel free to disagree if it doesn't go with the specifics of your relationship.

I wouldn't even know what to do in that situation. There is obviously a greater/deeper problem than just her worrying about the one guy. Try to soothe her fears but after awhile a line has to be drawn.

oh i have tried to talk to her about this but the feeling i get is she wants me out by the way she treats me which she is always going to her one friend who is a guy by herself for hours at a time which according to her that is ok and i have no say in that so i don't know what to do any more

Have you considered finding a gay-friendly marriage counselor / therapist? Sometimes that can be helpful, if both people are willing to try it (and you get someone that you both jive with).

Sometimes people express unhappiness about one thing, when in reality it's about something else. It's hard to know.

she will not talk to no one she says it is no ones business

That's distressing. It seems to me that a person who's not willing to talk about issues is possibly not really interested in a relationship. Or at least that has been my experience.

Of course there are also people don't want to do anything other than talk about issues!

Personally I like someone who is more or less in middle of those two things, but everyone has to decide for what they're willing to tolerate. :)

yea with all that i have been throught i have been thinking about going back to michigan i just can't take any more from her it gets to the point it is like walking on pins and needles where if i say the wrong thing she will blow up.

For the record, I am entirely speculating based on my own negative experiences.

However, most people who accuse their significant others of cheating either have a really good reason, are emotionally damaged by previous relationships, or are cheating themselves.

1. The really good reason might be that their partner is cheating, or is acting strange by hiding things. I know a girl who thought her boyfriend had found another girl because she had caught him lying about his whereabouts and he'd been really evasive when she asked him about it. Turns out her was buying her an engagement ring.

2. Someone with emotional baggage can work through it but you have to remind them that you're not the person that hurt them, and that you wouldn't. I have panic attacks 3 years into every relationship regardless of its nature and need to be talked down from it to carry on. If she's been really hurt before it might be resurfacing.

3. Cheating themselves is the most common and I only mention this because the guy hits on her and you hate him. Under those circumstances then, why would she think that you were the one cheating? The accusations are misplaced guilt. For some people, if they have cheated they have to imagine that their partner must have too.

Either way I agree with everyone else about trust being important and perhaps seeking a relationship counselor. Hope everything works out.