What began as one of the bigger characters in the Marvel Cinematic Universe has now become so irrelevant that they barely mention her existence.
Jane was one of the main characters from the first two Thor movies, but she began to bring less to the table during Thor: The Dark World.
It is important to note; however, that the Marvel Cinematic Universe has been changing pretty heavily since back in 2011 when Thor and Jane were introduced.
While Natalie Portman’s answer might be unexpectedly candid, it shouldn’t come as much of a surprise so Marvel fans.