If Elio subconsciously shares any part of his trauma with them.

He's a hypocrite in that he's willing to be trauma-dumped to, but not the other way around - mainly due to its intensity that would (understandably) be mentally-exhausting, in addition to the supernatural aspects of it - parts of which need to be omitted both for his and his listener's safety in the event that someone... unsavory happens to overhear. Also, therapists exist for a reason.