When we drill down and really look at what indecision is, the clearest description is that it is anxiety about uncertainty. Fuelling that anxiety is the spectre of making the wrong choice. It is this fear of what will happen if we make the wrong choice which is at the heart of this condition. Fending off fear is an exhausting activity, and stuck-ness along with its dark twin, powerlessness, will only feed that fear and will often feature a degree of depression as well.
Research tells us that cognitive behavioural therapy is a useful path when life is compromised by procrastination. When we tell ourselves persuasive stories about what will happen to us if we make a mistake, or, worse still, why we must never make a mistake, then little wonder we become paralysed. Using a gentle approach which challenges our faulty convictions, the grip of fear can be loosened and the person caught in the headlights can finally breathe out again and move.
The two related aspects in my response to your letter are, that your husband needs some quite urgent help with this very painful anxiety he is experiencing, and that you both need to be able to understand what the problem actually is and how to manage it.
Talk through with your husband about the fact that he is not in fact his indecision but that like a big black crow, procrastination has landed on him. Remind him what it is that you love about him and why you support a way forward to rid himself of this crow.
Solutions to indecision tend to lie in small steps. The first step in your case might well be about discussing the option to book a conversation with someone who understands how hard it feels and what to do about it.
The existentialist story of the starving donkey, trying to choose between two perfect and nourishing bales of hay in the barn, says it all. At its sharp end, this condition is disabling and, as you say, drains colour from life. We can afford to laugh at ourselves when we can't decide which choice of clothes will fit that social occasion - but to address the real price exacted by obsessional procrastination is sobering.
The good news is that it can motivate us to seek a remedy for this very human condition.