About 15. There are so many problems with logic here. I posted another reply with my own take, but yes, I suppose we were supposed to assume, as Robin had said, that Marian's marriage would be permanent. Except--logically--Guy was a traitor and might not survive the real Richard's justice, especially if Robin could convince him of Guy's assassination attempt. (Seemed possible to me at the time, but after ep 2x13, no way! Richard is an idiot!)

Minghella did cheat on this point in the script, I thought. When Robin rides into Locksley and Much yells that the king is an imposter, Robin says something like, "I thought so." I guess this was to help us understand why Robin did give up. However, we had no prior indication at all, in any of the dialogue or action, that Robin had suspected any foul play here.