I think there are two distinct things going on here. The 'opening-up to others' and becoming more comfortable and openly emotional is one issue. The other is his lingering emotional perception of you...something you said...how you reacted...something.
Regarding the people around him: When men reach a certain age or point in life, they may become more comfortable in revealing to the world what's inside, that they are emotional creatures and that they carry no shame for that. Its sorta like those Lavitra commercials where "you've reach that point in life where nothing gets you, holds you back...you don't back-down from a challenge." In other words: We are comfortable with who we are (not neccesarily true round here).
With you, there clearly is an un-verbalized, un-aired issue. They are usually (99.999% of the time) a lingering misinterpretation or misunderstanding of a word, a phrase, maybe a snicker, something that left a wrong perception within him.
Tween my wife and I, there were about 10 of these things (in both directions) that were significant enough to be easily considered 'open wounds.'
During the years of my non-disclosure to anyone, she/we were certainly exposed to plenty of CSA of other child-abuse stories on the news, at church, general public. I would usually get very sad but would always say nothing about the case. She would sometimes make comments commensurate with the myths of CSA survivors. When I heard those comments, I took them as ice-pick stabs directly at my heart. It made me feel even dirtier than before, less human, less valid as a real person, evil, deceptive and so-on.
I'm guessing the two of you have one of those things dangling over your heads right now. How you get him to open-up about it, I don't know...cuz I don't know the dynamic there.
None of this stuff may apply to you two, but I just wanted to give you one comparable case. I really hope the issue is revealed and can be put to rest.