My post was more in response to the seemingly mixed messages that might be confusing. I was confused to and I am sure a DB coach would help you better navigate. However, the point I hoped to make was some suggestions seen to relate more to "going dark" which is part of the LRT, and others are regarding detachment. In the book Michelle makes it clear that LRT is for when it is pretty much over. From what you have posted I get the sense that he is still unsure. Leaning toward S but not quite sure.
I think that before going dark healthy detachment should come first either way. Be a friendly neighbor to him but live your life for you. Throw yourself into work, hobbies, social events, anything. Date yourself. I see you are already doing some GAL. Whenever you find yourself trying to figure him out go find something to do to take your mind off of him. This part is about you. You aren't trying to make him miss you (though that might happen). You aren't trying to punish him (though you no longer should be making things easy for him). Definitely read DR. And books in codependency would also be useful, especially since you are dealing with someone with depression. It is easy to get sucked into their darkness.
The A to me sounds like a symptom. I know it must hurt immensely but try not to think about it. She won't make him happy. She's a distraction. Keep yourself busy so you don't have time to think about it.
40s 2teens M14Y BD-10/12/13 rec-1/14 BD2-5/14 rec2-9/14 EA disc-10/14 4/15-BD 3 and triangulation ensues Served with D6/15 MS forced to leave7/15 D agreement signed 8/16 final 5/17