One way to develop their relationship further is to give them new goals to achieve together. For example, they could decide to renovate Thornfield Hall completely and make it a symbol of a new beginning for them. As they plan and work on this project, they learn more about each other's strengths and weaknesses. They might also face financial difficulties during the renovation, which would test their relationship. Another aspect could be their spiritual growth. They could attend church together regularly and have deep conversations about their beliefs. These spiritual exchanges could bring them closer and give a new dimension to their relationship.
In fanfiction, their relationship could be developed through external challenges. Let's say there is a new character who comes to Thornfield and tries to drive a wedge between them. This could force Jane and Rochester to communicate more openly about their feelings and insecurities. They might also have to defend their relationship against the judgment of society. Maybe there is a scandal that threatens their standing, and they have to rely on their love and trust in each other to get through it. Additionally, exploring their physical relationship in a tasteful way, like the small affectionate gestures they share, can also enhance their bond.