So the BDSM community talks a lot about consent and trust. They're pillars of the BDSM relationship. Look around the forum posts and you'll see situations where the dominant (usually) is vilified for having violated the consent and trust of the submissive in some way.
And yet there is such a prevalence of justifying infidelity which, by its very nature, is a violation of consent and trust.
Or is someone who's not into BDSM somehow not worthy of that same consideration?
Because they're "vanilla", it's okay to violate their trust? Because they don't share our somehow superior mindset, their lack of consent is meaningless?
The partner of someone who's unfaithful has their trust violated and certainly hasn't consented. You may argue that their consent isn't necessary, because they're not actively involved ... but they're the one who'll be hurt.
When there's a caning, the one who feels the blows is the one who has to consent.
The same applies to the one who'll be hurt by infidelity, they haven't given their consent by-proxy to the person being unfaithful.
To you submissives out there involving yourselves with dominants who are hiding their activities from a partner, ask yourselves this: This person has already violated a trust and shown they're willing to hurt someone who hasn't consented for their own selfish desires -- can you really trust them?