Well, at first, it might be a bit of an adjustment. Natsu, who is used to being carefree and going on adventures, would now have to think about someone else besides himself and Mirajane. He'd start to see Mirajane in a new light, not just as a friend or a guildmate, but as the mother of his child. Mirajane, too, would see Natsu's growth and it would strengthen their bond. They'd have to communicate more about their fears and hopes for the future, which would bring them closer together.
Their relationship would likely become more intimate and deeper. With a baby on the way, they'd have to rely on each other more. Natsu would probably become more gentle and caring towards Mirajane, and Mirajane would feel more protected by Natsu.
Their relationship would evolve in many ways. Natsu would become more domesticated in a sense. He might start to do things like helping Mirajane around the house or getting things she needs. Mirajane would be more vulnerable around Natsu, showing her softer side more often. They'd also have a new shared goal of raising their child well. This would lead to them spending more time together, just talking about their baby, and planning for their future family. There would be more emotional moments between them, like when they feel the baby move for the first time, which would further cement their relationship.
The best chapter pointer here is Chapter 254, "Madwoman! She is definitely a madwoman!". It opens with Just when everyone thought that Jiang Yan wouldn't last long and would... and closes on A Jiang Li whose head was only filled with books and who never joked or....
If you want the clearest chapter reference, go to Chapter 264. Early on, Jiang Li first reassured her mother, then opened the chat box with Shen...; later, the chapter leans on She had just sent a message when Shen Lan's video call came through..
A practical answer is Chapter 238, because it turns the idea into a concrete scene. The chapter opens with Jiang Li was actually first on all three leaderboards?!, adds pressure through This will be the final component in settling their good score!" The guests..., and ends on And, to Zhou Xu's.
Chapter 219 is the strongest chapter-level answer because it starts from Qi Tianyu was somewhat freaking out. and follows through on Having any yield at all was already the show giving them face..
If you want the clearest chapter reference, go to Chapter 210. Early on, This was Zhao Lang's first public appearance.; later, the chapter leans on He was dressed in a set of black and white local attire, with a simple....
If you want the clearest chapter reference, go to Chapter 207. Early on, After finishing, Sister-in-law Lan quickly took out the Good Evaluation...; later, the chapter leans on Su Yinwan didn't feel anything amiss and shyly lowered her head, fully....
The best chapter pointer here is Chapter 258, "Explosive! Jiang Li and Director Sun Are Having an Affair!". It opens with Just when everyone in the livestream room was immersed in the lively and... and closes on Is Jiang Li really having an affair with Director Sun?] "[What the hell?.
Look to Chapter 226 for the clearest answer. It begins with What was all that before then?, keeps building through Jiang Li quickly tapped the screen twice, and a red packet link that was..., and lands on Are you sure you can be on the list of winners?] Zhou Xu: [?.
The best chapter pointer here is Chapter 244, "Come, Let Brother Give You a Kiss". It opens with LOL, Director Sun can't seriously think his sappy quotes are working, can... and closes on I don't really have much to say..
Chapter 224 is the strongest chapter-level answer because it starts from Jiang Li, ranked number one, was directly taken by the staff to an elegant... and follows through on After all, the fans of Su Yinwan next door had already thrown down nearly....