I said that on the emotional level it's more similar.
Personally the only one I was able to imagine wasn't as pleasing as you present it. Knowing that I'm probably not the best lover on Earth, nor the next Rocco Siffredi, what can be emotionally reassuring is that by cheating with a girl she'll obviously never be with someone that have a bigger dick, or that is better lover than me. But, as I said, in reality it's far to be a pleasing thought.
What level of insecurity, trust issues, or low self esteem, did it need to imagine that a girl can leave you just because she found a bigger dick or a better lover ? Just having this thought, even if it's indirectly by thinking "by chance she cheat with a girl", is the negation of all possibilities that she have sentiment for you.
This while, well... Who know, perhaps she love you, but also want to have an orgasm time to time, and feel less guilty being with a girl, than sitting on a dick. After all, she probably know you and your fear to raise a baby that isn't yours. It's by love that she cheat with another girl, in order to not be angry due to the lack of orgasm, while doing her best to appease your fears.
But all of things hail from biology, sexual urges especially, and man like to father their own children.
Of course, there's the emotional appeasement to know that she'll not be pregnant because of another guy... But as I said, this can be easily solved if she agree to only do anal or give blowjobs. So, once again since you haven't answered, is it not cheating in this case ?
Since what seem to emotionally reassure you is that, is it really emotionally better to wonder if she had someone's dick in her mouth before she french kissed you today, or to know that she'll probably never be constipated, due to the number of dick that pass through her ass ? But, more important, is it really emotionally reassuring to know that she's stupid enough to fuck raw another guy than you, and so will perhaps one day catch AIDS, then transmit it to you ?
In the end, not only you haven't answered my question, but you also totally passed the fact that there's worse to fear than her coming back with a baby. In what world one fear the possibility to have to raise a baby that isn't his, more than he cherish his health ? This while thinking that his girl would necessarily be stupid enough to not protect her own health.
I'm sure that there's something to conclude regarding your views about women. But like you said that you aren't sexist, then you're just someone who don't know that, while protecting against STD, condom also protect against pregnancy.
So be reassured, you'll not have to feel shame because you're qualified as sexist. In fact you are just idiot, and there's plenty like you.