I went through my screenshot folder and read all my conversations and stuff. Everything was exhausted. The only possible variable that might be an issue is when we found the warden-constable badge? This was my game order. Probably means nothing, but still.
- Lone Warden
- exhaust all conversations with him in Haven
- recruit all the other companions
- finish sign of wardens, start flirting after
- Hushed Whispers
- Chat about Blackwall's future self in mage time travel
- In Your Heart Shall Burn
- Conversation on Skyhold ramparts (he pleads to not continue relationship)
- Chat at barn about "You are who you choose to follow"/chevalier story
- Apologizes for pushing away, acquire quest to find the warden-constable badge
- Hawke/Western Approach quests
- Into the Abyss
- Blackwall talks about Grey Wardens and Corypheus, evasive answers afterwards on how to kill archdemon
- Find the warden-constable badge finally, Blackwall appears in Skyhold bedroom, romance locked in.
- Wicked Eyes & Wicked Hearts, do the eluvian thing with Morrigan afterwards
- Grab a drink, he disappears in the morning
- Revelations
- What do I call you now? Scrambled eggs, huh? (No "truth" investigate tree.)
I'm wondering if I should have done the warden-constable badge quest before doing the Grey Warden stuff? Other than that, I have got no clue at all.