When we go into flashbacks we(players) are transported into the full story, but i always understood that he witheld a lot of it(so did Melissa talking about young Emily).I agree with you on that.
But even with "leaving out some details", as usually a gentleman should do, it should have been apparent from his story, how happy he was there, how emotionally involved he had become.
So Erynn should have sensed that.
Erynn does sniff something which is why she has those thoughts about how much he's holding back and asks if he's happy to be back in town?