Care to elaborate?

Suspicion is often linked with the guys nature

Is he the sort of guy that always looks single and doesn't mind acting it?
Does he enjoy flirting, has he done anything that gives you reason to be suspicious..

this guy that you are dating, is very lucky to be with you, after all you care about him alot. im gonna tell you straight out though- your man might or might not be cheating. the way to find out is to make him fell bad, tell him how much you love him and how much you care for him. then tell him he hasnt been acting the same lately.after that if he doesnt crack... ask him if he's cheating, and tell him that you will not tolorate the bull SH*t from him.  :-X

Yes, think we need to know specifically what is it that he's doing that makes you suspect he's cheating on you.