Re: Why won't he file?
I don't have any new insights into why your husband is dragging his heels, but I do have a suggestion to help speed things up a bit.
How about explaining why it's in his best interest to sign, file, and be done?
I'm not a lawyer, and I don't know the laws where you live. It might be worth looking into the rights that spouses have where you are. Whatever those rights are, he may not be comfortable sharing them with you at this point:
1) In some places, spouses inherit property when the other spouse dies, unless the will says otherwise. And even if the will does say otherwise, the spouse can contest it. In some areas, the spouse often has a chance of winning a suit like that.
2) In the US, at least, spouses are jointly responsible for any federal student loan debt or tax burden. So if you owe money to the government, he does, too. (There are innocent spouse protections, but, from what I've heard, it can be very challenging to prove innocence.) That's a pretty good disincentive for him to stay married. (I know that, once you divorce, you get sole responsibility for student loan debt. I don't really know about taxes--a tax lawyer could give you better advice on that.)
3) In the US, If there are joint accounts, both spouses are responsible for the balances, and any screw-ups affect both of the spouses' credit ratings. If you were to use your joint account to get a credit card, run up a bunch of debt, and then not pay it back, your husband would be on the hook for that money. Does he want to risk being in that position?
4) Do you guys have joint property? Where you live, could just one of you sell, give away, or otherwise basically do what you want with that property? If so, it's really in his best interest to sign and be done, to make sure that he gets control over whatever ends up being his.
5) Do you have kids? If so, working out custody formally may work out far better for him than simply trusting that you'll be reasonable, however he defines "reasonable."
It's awful that he's keeping you hanging like this. Stay strong. Let us know how it goes, once his two weeks of hemming and hawing are over.