Re: Player problem - opinions ....
Correct me if I'm wrong. But it sounds as if Thrudd did not have any say in how his character reacted to the woman who was trying to seduce him and that he basically was forced to break his vow of chastity based on a die roll. If that is true, I think the GM handled the situation badly. If my character were forced to do something completely out of character based on a die roll, I would be upset. For another character this might not have been a big deal. But if the character is serious enough about his vow of chastity to take a disadvantage for it, he shouldn't be forced to drop his pants everytime some hottie gets a lucky die roll. He should have some say in how his character reacts to the situation. Isn't that how roleplaying is supposed to work?
Also, there are other possible outcomes to a successful seduction roll than to make the paladin get naked with a woman of ill repute. For example, he could have succumbed to a passionate kiss before pushing her away and fleeing a compromising situation.
I don't really think you did anything wrong. It sounds like something that would fit with your character's personality.
Regarding his reaction, I think there were much better ways to handle it, especially considering his character wouldn't have known that your character was involved. I think murdering an old friend because of his moral failure was even more out of character than breaking his vow of chastity. It would have been more appropriate if he had role played out his grief and attempted to do penance like you suggested. Oh well. At least he took his character's vows seriously. Maybe you should give him some credit for that.
Anyway that's my 2 cents.