What woudl he wnat with the women at Barton cottage? I can't see that JA does not intend us to think that he was out shooting, which he loves, and happened by when Marianne fell. I can't see what on earth he woudl want with people like the Dashwoods, other than some pleasant society. As for his watching Marianne in London, given that he knows she's been writing to him, naturally in his circumstances he's bound to be nervous as to waht she might do and might well want to see what she's up to while she's in London... He is watching her from an opposite motive to a stalker.. he doesn't want to be closer to her, he wants to make sure that he avoids her.