1. Jo was Dean’s biggest regret; we see this in “Defending Your Life,” we know that Osiris only asks about things that Dean regrets. Osiris asks several times about Jo’s feelings for Dean, in comparison he only asks once about Jo’s first case; or the one that started it all. Showing Dean regrets something about her feelings for him. Which would either mean he feels he lead her on, or he he would feel guilty for never reciprocating. Given the look he gave her when he joked about her “massive crush” on him, he felt guilty for never reciprocating.