We all saw that slap delivered to Loki by Jane Foster in the new Thor: The Dark World trailer, so I think it's safe to assume that the astrophysicist isn't going to be trusting the God Of Mischief anytime soon, despite them being forced to work together to combat a common enemy. In the below video interview from D23, Portman discusses this, while also commenting on her character being the "stranger in a strange land" this time, and the darker tone we can expect from the Marvel sequel.
On how Jane feels about Loki as an ally
"I don't think she's as quite as forgiving as Thor is. Often times we protect the people we love more than we protect themselves. But, he's helpful in some places. Evil people can think like other evil people."
On how Jane feels after coming to Asgard
"Things that she's marveling at seem like high technology to her are like kids toys [to them] and they are such an advanced species that even though she's this astrophysicist she's totally inferior to all of them. So, I think it's a good humbling experience for her."
On the different tone we can expect for The Dark World.
"It's much grittier I think because they chose to shoot in real places much of the time. A lot of the villains world was shot in Iceland, so it looks like real places as opposed to some [place] drawn on a computer. It's a lot darker in tone maybe, but still quite epic and entertaining."