Detaching is not something that separates people from their relationships - it is about emotional detachment where you give each other room in the relationship to exist and be who you are. To coexist peaceably. That requires compromise, goodwill, and maturity. IMHO, the traditional M vows say something like - the two become one - gets misunderstood to mean two people have to become one person or the same. But it really means that two people have to work as a team (one unit) and coordinate daily to meet responsibilities etc.
Going dark or physical separation may or may not result in a permanent break depending on the experience of it. If you separate and miss each other then it brings you back together. If you find you life is better without the other person then you may want to explore the reason for that feeling and may decide to make it permanent or not. (Sometimes changes can be made to accommodate the reason which keep the M together)
Signs to look for - you have to make your own list of what you want to see. I think there is a chapter on deciding what you want in the DR book. Being specific helps a lot - i.e., I have signs like - being sober, having a convo without arguing, showing concern for my health, welfare, the kids, talking in a respectful manner, not mentioning the D word, does that help? Make up a list that applies to your sitch. Then think about what are the ways you could let him know the door is open? That you would like to spend time with him etc.
My H often pressures me (tries to control me) and when he started asking me if I would meet for coffee at a neutral location -that was different for him. When he says he needs to talk to someone please call back if available -that's different and when it is important - that is also different. Does this help? You may have to adjust the list a few times or discuss it with your DB coach.
Not to drag this out but I posted on a DA thread this explanation from Alanon about what is detachment -
if your H falls on the floor next to the bed drunk- to pick him up and put him in bed = enabling (the opposite of detach) if your H falls on the floor next to the bed drunk - to ignore him = not caring (not detach) if your H falls on the floor next to the bed drunk -to put a blanket over him is detaching.
...and my joke for the day to add to this diddy is," what do you call it when it is you that has fallen down drunk on the floor next to the bed". Hope you can laugh at that one. If I offend you I am sorry - it just slipped out.