I'm surprised that you wrote about their status. I might overlook something, but did episodes drop a hint about their fate of the marraige, or something? Because I don't think any episode comfirms that unless, like I said, I might miss it.
Well, In It Isn't What You Think, Toby slept with Lily, and then Lily said "You are my first divorcé." From this, I assumed that Toby has gotten over Nikki and moved on with his life. I might be wrong as well, but I believe that it is safe to say that Toby and Nikki are officially broken up.