Well, it depends. If you're doing the entire arc solely from Ed's POV, then yes, it's going to take some figuring out on Ed's part to completely understand the dynamic, and why Roy shut himself off. And, from where I stand, if I were Ed, I don't think it'd be possible (or honorable) to seduce someone into coming around, so to speak, if there's an underlying issue that must be addressed. Obviously the seduction is, in its own way, both apology and forgiveness, after and before the two facts.

However, if you're not going solely from Ed's POV, then you have two options. Either Hughes plays a role as Roy's foil, or it's Hawkeye. Either one could bring different elements to light, while never entirely touching on the actual issue - as I wouldn't expect Roy to spill his guts to either, but neither would be fooled by his dancing around the topic, either. It could be as simple as Roy straightening up his paperwork and Hawkeye coming in, dropping off stuff to sign, and leaving with the words, "he doesn't hate you, and he won't." or something simple...

Just some thoughts, since I'm full o' brainstorming while preparing for the Big Scene From Hell. wahh.