Almost all the guys - the owners. And if the guy there are constant suspicions that it is trying to deceive, to hide something, then to change it will be very hard. For people don't need a reason to be jealous, they find it in any situation. To prove his innocence of treason is practically useless. In such cases, can only help the conversation and placing all points over "i". Should negotiate with him clearly once and for all that suspicion and quarrels can only destroy the idyll. In fact, cheating does not even smell.
Sincere explanations can help not always. You can arrange a personal acquaintance of the guy with the person to whom he was jealous (better to issue as a chance meeting). This can be a colleague or a classmate who was not going to go into other people's relationships, just not in time called or texted. This situation can also be resolved without resorting to the introduction of two people, and, for example, typing the phone number of the person to whom jealous. Turn on the speakerphone. Maybe the guy will realize that any additional relationships, except for manufacturing or business, you is not in sight.
At the very least, when it's running out of options and the guy just doesn't want to hear anything, you can find out where in the city there are firms offering services of detection of deception using the polygraph. It's pretty expensive, are they not everyone can. But one your offer or consent to be tested on a lie detector can filter out all his doubts. If he liked a solution, then why not arrange a little adventure, and at the same time to see how this detector works. It will be a very entertaining experience.