The baby could bring them closer. They now have a shared responsibility and a new bond in the form of their child. They might spend more time together taking care of the baby, which deepens their connection.
In the fanfiction, the baby changes their relationship in many ways. Initially, they might be a bit overwhelmed and not know how to support each other properly. However, as they see each other's efforts in taking care of the baby, they gain a newfound respect for one another. The baby also becomes the center of their world, and they start to build a family - centered relationship, where their decisions are often based on what's best for the baby and their little family unit.
Well, at first, the baby might cause some strain. There could be arguments over who does more work, or differences in how they want to raise the baby. But as time goes on, they start to understand each other better. They learn to communicate more effectively because they have to for the sake of the baby. Eventually, their relationship becomes stronger and more loving as they both grow into their roles as parents.