OMG!!!! If going out to dinner with an individual of the opposite sex is considered "cheating", then I've been a sinner for MANY years
!!!
Mostly because of the business I'm in, most of my colleagues are men (the ratio is about 8:100 - 8 woman:100 men). Throughout the years, I have become good friends with many of them regardless of their status (single, married, divorced, etc.) - or persuasion (as a matter of fact, I have a fair number of gay men friends as they are as interested in the arts & travel as I).
My husband always knows if I'm going out to dinner with a colleague/friend, and he has never questioned me about it. I think it comes down to *trust*, and I think he knows that I'm not the type to "cheat" (frankly, I'm not a good enough actress to hide my feelings!).
One of the major differences that I've seen working in the US versus Europe, is that we in the states have become almost TOO politically correct. Mind you, I'm not saying that we should be able to go around making inappropriate statements or harassing individuals, but I think we also have a tendency to *read into* things that may be quite innocent. Just because you're with someone (whether it be dinner, a movie, theater, etc.) ... it doesn't necessarily mean that you're having an *affair* with that individual!!