It's possible, but it's not a good idea, no matter how friendly the divorce may be. Later, one of you might claim you didn't understand what you signed or that the lawyer or the deal was really one-sided. When claims of unfairness arise, judges usually don't like situations where there was only one lawyer. If your case is simple, both spouses might represent themselves in negotiating a basic settlement; then they might hire a single attorney to draft it.
A note to attorneys. I see no ethical problems with (and I have in fact done this on several occasions) representing a party in a divorce and then meeting with the other pro se spouse to discuss settlement and/or other legal issues. HOWEVER, I make it very clear to the pro se spouse that I do not represent him/her.