There's a number of variables beyond the control of any one party and in these circumstances deals can take longer than you might think.
On Everton's side the variables will most likely arise from differences between shareholders as to what price to accept and who is offering the best deal going forward. Equally each shareholder may have different priorities be that price or succession plans.
On the buyer side if there's a consortium (as seems likely), outside of small variables, any changes to the deal will have to be communicated to members of the consortium. Equally if there is debt involved the lenders will demand to approve any changes to the proposed deal.
Then we have the stadium situation which may be quite fluid - material changes will significantly change the value of the deal.
Finally although there appears to be a favourite bidder, other bidders can come in late on the deal, a small premium on an agreed deal can make a big difference especially if one of the controlling shareholders is seeking to maximise the value of the deal.
All speculation of course, but there is likely to be legitimate reasons for the deal time stretching.
A little more patience required I think.