My heart breaks for you as I am on the same roller coaster and pins and needles as you are... but I have achieved peace and serenity even knowing that our lives are so uncertain. The disease is cunning and powerful and only dedicated ACTIVE recovery keeps the A from sliding down the slippery slope of relapse.
The GREAT news is that your A has the tools and he is very capable of regaining his sobriety but it would be very healthy for him to start over at step one and find out where he missed something!
Was it active service? Was it daily inventory? Daily prayer and meditation with his HP of his own understanding?
A puzzle piece got lost... it happens! Dry your tears because this valley may get him on the REAL path God has for both of you!!!! Seriously ... see the hope and the future of a spiritual revelation that may change his and your life together to become deeper and richer in meaning and real recovery.
This has happened for me... and I am the worst know it all and the one thing that I have learned in recovery... I do not know it all and in fact know very little. My HP wants me to learn more about me and about those I love and others who are struggling.
If retreats have been good at "firing him up" then I strongly suggest that he prayerfully consider whether his HP wants him to be a STEADY volunteer at retreats! Maybe listening to XAspeakers or hosting others to listen to those together is something to consider. We must give back to keep what we have been given ...
You know this... it works if we work it. Sounds like he has a willing heart and that itself is a very, very good thing.