We drifted into something even more separate, but started along very similar lines. It’s too late to change where we’ve ended up, but looking back I feel quite sad we allowed it to just happen. It has to be said that as the changes happened gradually I didn’t regret them at the time, but they snowballed, and left us barely together, and like you, I have a feeling of loss.
If I had the time again, I would try and address the issues as they arose (like why it was suddenly easier to have separate rooms), rather than just let the relationship wither away altogether. I'm left in limbo; married, but without a partner or companion. I don’t want anyone else, but so wish we’d tried to keep what we originally had.
If you still want to be with your husband, rather than by yourself, I would really try to talk about how you feel, and see if you can get back some if the togetherness.