To be fair, I don’t think that the 10 commandments are meant to cover ever possible conceivable “sinful” act and enumerate it, but rather to put down a broad code of conduct for public life (originally for Jews, but now for all the people of the book). I’m fairly certain it’s covered under at least a couple of them, though… at least under adultery (which I don’t think is just strictly adultery, cheating on one’s spouse).