My girlfriend is so perfect to me to the point I think she is cheating how can I relax ?

If she has never done anything that causes you to not trust her, then she does not deserve for you to be distrustful of her. Plus I think you need to recognize her flaws with careful observation, so that you are able to let her get off the pedestal you have put her on. Nobody is perfect and everybody has flaws, it is best to recognize the faults of your loved ones along with their good traits so that there is a balance. Because only when there is a lack of this balance is there place for insecurity in any kind of relationship. Love their faults as much as you love their best traits. Only when you find yourself doing that for someone do you truly love them.

Maybe talk to her about it, I know that it might be an uncomfortable conversation at first, however, if you explain to her how you are feeling and talk to her about it then it would most likely make you feel more at ease. By talking to her about it it means that you would be able to hopefully talk about things like this in the future, even if that is uncomfortable at first, but hopefully that she will understand where you are coming from and she will be able to comfort you and by doing so, help you relax about the situation that you are in.

Well if she is perfect to you i doubt she is cheating, when people cheat you can tell when they start to care less or when they are less perfect, because their attention or interest is elsewhere or divided, so someone being perfect is no reason for concern, you should only worry when she stops being perfect. If you think its too good to be true, look at it this way, she wouldn't try that hard if the feelings weren't there, its more of a all in approach than a deception, so i suggest that you hold on to her because like you said, she is perfect.