KING: Now, listen to this. Sit down. Be seated. No courtship, Thomas. You're my friend, are you not?
MORE: Your Majesty.
KING: Thank God I have a friend for my chancellor. Readier to be friend, I trust, than he was to be chancellor.
The king doesn't realize that certain things are more important to More than friendship. He's perfectly willing to sacrifice a friendship for the sake of his religious principles.
CROMWELL: What kind of thing would you repeat or report?
RICH: Well, nothing said in friendship.
CROMWELL: Do you believe that?
RICH: Why, yes.
CROMWELL: No, seriously.
RICH: Well, yes.
CROMWELL: Rich, seriously.
RICH: That would depend what I was offered.
Rich acts like he has principles, but look how quickly the ruse collapses. All that Cromwell has to do in order to get him to betray More is to ask him if he's serious about not betraying him… twice. Basically, Rich is a hollow man.
DUKE: I am your friend. I wish I wasn't, but I am.
MORE: What's to be done then?
DUKE: Give in.
MORE: I can't give in, Howard. Our friendship's more mutable than that.
DUKE: Oh, the one fixed point in the world of turning friendship... is that Thomas More won't give in.
The Duke is a far better friend to More than Rich or King Henry. But, still, their friendship is a relative thing when it comes to the question of religious principle. Friendships can fade away or die instantly, but More's faith is so central to his sense of being that he can't compromise on it or budge at all. His love for God's law is at the core of his being.
DUKE: And who are you? A lawyer! And a lawyer's son! We're supposed to be the proud ones, the arrogant ones. We've all given in! Why must you stand out? Goddamn it, man! It's disproportionate! You'll break my heart.
MORE: No one is safe, Howard, and you have a son. We'll end our friendship now.
DUKE: For friendship's sake?
Tragically, More has to abandon one of his only true friends, for both their sakes. The Duke can't be sympathetic to a traitor, and Thomas simply can't swear to the oath as the Duke has done.
MORE: We've had a quarrel since the day we met. Our friendship was mere sloth.
DUKE: You can be cruel when you want, but I've always known that.
More actually has to verbally attack the Duke (he even provokes him to try to punch him shortly thereafter) and try to hurt his feelings just to keep the Duke safe and give himself the space to continue following his principles. It's painful and is one of the real obstacles in More's journey toward martyrdom—more of an obstacle than any of Cromwell's machinations.
DUKE: Oh, confound all this! I'm not a scholar. I don't know if the marriage was lawful or not... but damn it, Thomas, look at these names. Why can't you do as I did and come with us for fellowship?
MORE: And when we die, and you are sent to heaven for doing your conscience... and I am sent to hell for not doing mine, will you come with me, for fellowship?
Does More think the Duke is "doing his conscience"? There might be a little irony in his suggestion that the Duke will go to heaven for being true to himself, while More would be at rest. But, at the same time, the Duke seems like a good guy—just not someone who's overly concerned about whether the Catholic Church is the true church or not.