Be honest: do you think it would HELP you or just HURT YOU FURTHER if you found out she was having an affair?
Would it be a dealbreaker for you?
She very well may not be -- I'm pulling this number out of thin air, just based on my experience, but I'd say that about 15-20% of the situations that present these symptoms do NOT involve infidelity, and your wife could very well be one of them. There are also situations where it has been CONTEMPLATED, and the guilt of it and the sheer amount of time the thought of it has been dwelt upon by the unhappy spouse can make them ACT as if they are already deeply involved in at least an EA.
It could be unrequited.
Think Saddam and his WMDs. WE thought he had him, the UN though the had them, our ALLIES thought he had them, and he even ACTED like he had them. Why he would allow everyone to think he had them, ultimately to his own demise and death, is still perplexing.