No judgement, but no.
I'm big on total honesty and transparency in relationship, so for me cheating is a deal breaker. I have some pretty strong opinions about dishonesty within relationships in general - to me it's better to be open, transparent and single than in a relationship peppered with dishonesty of any kind. When everyone is their authentic selves in a relationship it allows you to choose whether that person and the things that they want are a good fit for you. A charade where they're doing a bait and switch to anyone involved robs others of their own independent right to either choose to be continue with the new information, not, or work on compromise. To me it's about respect.
For those that are on the "deal-breaker side" - is there any configuration in which you think that cheating is less abhorrent? Are there grey areas, or is it black and white? For example - a husband has a mistress because his wife is paraplegic or has advanced stage cancer. He loves her, doesn't want to hurt her, but also doesn't want to burden her with his sexual needs.