The first signs Justin wasn't his normal self came when he showed up alone to his usual Wednesday night service ... this only hours after we broke the story of Selena's emotional breakdown.

Justin's been attending church with new wife Hailey Baldwin -- just as he did when he was dating Selena -- but Wednesday, the Biebs was flying solo and he needed to be comforted by friends as he was leaving.

It's interesting ... Justin and Hailey typically do their own thing coming in and out of services, but last night he was surrounded by his church buddies. Justin, messy hair and all, clearly looks like he could use the support.