I am convinced that the original plan was still to marry immediately--until Sir Walter announced that he would not give Anne her portion. At that point, it was obvious they could not marry, since CW had saved absolutely nothing of his prize money, and had no promise of even getting a ship. Anne's portion of either 10,000 split 3 ways or 10,000 total (however we read that; I tend to read it as 10,000 for Anne) would have been enough, I believe, in their eyes to justify immediate marriage. Anne has already stated that if CW still wanted to marry her, she fully expected he would have returned to do so once he earned his first few thousand soon after.

I'm thinking that in LR's eyes, and in eyes of the Elliots, this would not have been much to justify a marriage.

So, here's what I'm saying: they think "Hey, we've got a dowry of 10,000; what's to stop us?" Then, when Anne realizes that they have absolutely NO money, and not much of a prospect of getting any, she allows herself to be convinced that they are being foolish and ridiculous.