Why does Hari Seldon not see his granddaughter for the last few years of his life?

Question

At the end of Forward the Foundation, Hari talks about sending Wanda away from Trantor:

“No, Wanda,” Seldon replied, his voice choked with emotion. “I don’t want you to leave, but it is the only way. You and Stettin must isolate yourselves from the crude physicality of Trantor.

and he is vague about where the Second Foundation is (or will be) located, and uses the Star's End clue that is used in earlier books:

“But, Grandfather,” Wanda said as she stood with Palver, preparing to leave. “Where shall we go? Where is the Second Foundation?” Seldon looked up and said, “The Prime Radiant has already told you, Wanda.” Wanda looked at Seldon blankly, searching her memory. Seldon reached out and clutched at his granddaughter’s hand. “Touch my mind, Wanda. It is there.” Wanda’s eyes widened as she reached into Seldon’s mind. “I see,” Wanda whispered to Seldon. Section 33A2D17: Star’s End.

He goes on to note that he's not even seen Wanda:

I miss Wanda. It has been many years since I’ve seen her, sat with her quietly, holding her hand. When Wanda left, even though I had asked her to go, I thought I would die of heartbreak. That was, perhaps, the most difficult decision I ever had to make and, although I never told her, I almost decided against it. But for the Foundation to succeed, it was necessary for Wanda and Stettin to go to Star’s End.

What's Asimov doing here? We know that the Second Foundation is…

on Trantor itself, at the Galactic Library, not far at all from Hari at Streeling University.

So why all the obfuscation at this point?

I assume he's trying to cater for people who might read the series in chronological order: they won't know that, at this point.

But surely he goes too far, with the "many years since I've seen her"?

Or is the point that…

it's important for the Second Foundationers to be entirely socially isolated from Trantor, even to the extent of having no contact whatsoever outside the Library?

I don't recall that being discussed in detail, though.

Answer 1

Because the First Foundation must be isolated from any conception of psychic powers and the Second Foundation from knowledge of robots

For reasons that no doubt make sense psychohistorically, Seldon has designed the First Foundation to be entirely oriented to the physical sciences. In "The Encyclopedists" Hardin notes that only one psychologist accompanied the First Foundation exile to Terminus (Bors Alurin) - and Hardin suspects that he didn't teach everything he knew. Ebling Mis also noted the intense secrecy of the Second Foundation, designed in since Seldon's day.

Visits from Wanda to Seldon risked exposure of her growing powers to others in the First Foundation group, and even visits of Seldon to the Library might reveal something, raising questions in the minds of the First-Foundationers-to-be about what Seldon's grand-daughter was doing (especially as Wanda and Palver recruit more telepaths and work on developing their powers). Better for the Plan, if she disappears, allowing the others to hypothesize that she has become estranged, than risk the fate of the entire plan.

Furthermore, Seldon has secrets he is keeping even from Wanda - the nature of Dors and Eto as robots, for one. This knowledge might affect the Second Foundation's development -- and the developing powers of the Second-Foundationers might reveal that knowledge if too much time is spent with Hari.