Maybe you could make a list of little things that have changed in between the two of you, Little things you have changed about yourself and ways that you changed interacting with the H over the past few months. To keep as a reminder so there is no back sliding or at least you recognize it if there is. It may also point to behaviors that did not work for you in the past and give you a little insight into what may be working.
Also the trust thing. In truth none of us no for fact our spouse will not walk out tomorrow. We think we do. But look how many people on the WAS board never saw it coming. It is a chance we all take. The fact that he has already left twice will never go away. But maybe this time you and him can come to a place of understanding of what is going on with him. And in time the fact you stood beside him and never gave up. May allow him to see you for all the love you give him and he will be able to give it back double fold. Take it slow. They say time heals all wounds. If not it at least dulls the pain. Here is hoping the two of you figure it out. And build dreams for a long running future