Wasn't it settled that he had at least the testimony of Chad's own belief in a settlement?
Strether found himself treating Chad's profession that they would get on as a sufficient basis for going to bed.

He hadn't nevertheless after this gone to bed directly; for when they had again passed out together into the mild bright night a check had virtually sprung from nothing more than a small circumstance which might have acted only as confirming quiescence.
There were people, expressive sound, projected light, still abroad, and after they had taken in for a moment, through everything, the great clear architectural street, they turned off in tacit union to the quarter of Strether's hotel.

"Of course," Chad here abruptly began, "of course Mother's making things out with you about me has been natural--and of course also you've had a good deal to go upon.

Still, you must have filled out." He had stopped, leaving his friend to wonder a little what point he wished to make; and this it was that enabled Strether meanwhile to make one.

"Oh we've never pretended to go into detail.