Trial separation isn't the death knell for a marriage. In fact, it most likely will give you both breathing room to think about the relationship, and also reflect on what each of you want. Well, if you're here and DBing, that is part of the process, but I hope that he also uses the time during separation to do the heavy lifting.
Give him space. Tons of it. Don't pursue.
Are you sure there is no A happening? As NicoleR pointed out, her H took the time apart to be with other women. Not saying that that is your case or your fate, but I would see if you can suss out any intel on that - don't go crazy snooping, but if something doesn't feel right, then it's most likely not right.
Hang out with him on Saturdays and do dinners if that's what you can handle emotionally. Start living your life and that your dinners and Saturdays are with some acquaintance you know. Act 'as if' and really get on with your life. You can't fake this.
My W wanted to do weekend dinners and she never followed through with them. I wasn't sure if I wanted to do them, and in the end I didn't, but she never brought it up again so it became a moot point.
Follow Sandi's rules and take it slow. Give yourself a break and focus on yourself. It's YOU time. He's gotta figure himself out.
