Interesting thread/discussion. To the OP, I think the fact you are asking if you are a bad person - for the record, I don't see "bad person" but I do see "human" - means you are struggling internally with making the right decision and just the fact that you are struggling means you already have your answer. Frankly, I'd be more worried if you understood the dilemma and thought, "Fuck it, I'm going to do what I want."
hunnus2000 brings up an interesting thing. "Anything you can't divulge to your SO is a form of cheating."
I want to take this out of context and explore this a bit further. I get you, hunnus, were setting up the joke about your SO's ass, so this isn't directed at you at all. But I know people who believe that sentence above 100%....meaning they share EVERYTHING and leave out NOTHING. I think in my younger days I may have...when dating and romance and relationships were new and exhilarating and thinking about the long haul of what it means to be a lifetime partner. But with the hindsight of aging, I just don't think it holds up. And maybe this comes down more on an individual style and how we relate to others but frankly, I don't WANT to know EVERYTHING. Important stuff - yes. But EVERYTHING? No.
Do I want to know my spouse finds his coworkers breasts distracting? No. If he acts on that thought or thinks he might, yes.
Do I want to know if my spouse lost his cool with his brother about a mulligan on the golf course and they aren't speaking? No. If he's struggling with how to mend fences and wants some advice or some support? Yes
Do I want to know if my spouse cleaned up a stain on our new carpet because my son dropped a cherry and left it there overnight and he wanted to prevent a meltdown (on my part)? No. If I see it anyway and want to know how the hell it happened and ask a direct question? Yes.
And there are plenty of things I keep from my spouse. Not earth-shattering things - not relationship breaker things. But many things that he a) probably doesn't really give a shit about or b) would only add to the jumble of things he's already dealing with and aren't really important to him.
So for those of you in longer term relationships, how do you feel about sharing everything? Have you and your SO had conversations about this?
I know at one point around finances me and my spouse had talked about it being fine to spend on whatever but anything over $500 had to be discussed ahead of time. We have always been pretty good about talking about money though, so we have trust there. But I know for a lot of couples money is a hot button issue. Sex is too. If one of you has a higher or lower sex drive are you sharing all of that - EVERYTHING - with your SO or are you just dropping hints and/or avoiding conversations around it?
[Edit to add] The correct response to the question, "Do these pants make my ass look big?" is ALWAYS "Oh hun, I love your ass in anything, you know that."