The reason why some relationships do not last long is because of jealousy and distrust. In this case Jane's rival is Blanche Ingram. It is true that Jane is not envious of Blanche's mind, but she resents Blanche's ability to gain the complete attention of Mr. Rochester. It is already evident what Jane's reaction will be when other, more desirable women, are in Rochester's presence. Neither of them has publicized their feelings for each other yet they cannot bear the sight of the other with somebody else. Rochester emits his jealousy as well, when Jane receives news of Mrs. Reed's illness. He does not agree with her decision to leave Thornfield, because he is afraid that she may not return. He is resentful of Jane's relative's for the reason that he knows that his bond with her could not compare to her family ties. He cannot compete with that kind of familial connection. He only has money to give, and money cannot buy the time Jane spent with her relatives, no matter how badly she was treated.
A factor that could complicate a new romance developing is Jane's lack of experience with men and Rochester's willingness to take advantage of it. The men she has come across thus far have treated her with cruelty and disdain. For example her cousin John Reed bullied and tortured her from morning until night when she was only a little girl. Jane was never presented with much affection or care by her benefactress, Mrs. Reed. So