Well, there's often the theme of unexpected love. Given their initial relationship as just neighbors and friends with very different lifestyles, the idea that they could fall in love is unexpected. Also, there can be a theme of acceptance. They have to accept each other's flaws and differences as they enter into a romantic relationship. For instance, Sheldon has to accept Penny's party - loving nature, and Penny has to accept Sheldon's OCD - like tendencies.
The theme of growth is also common. As they fall in love, they both grow as individuals. Sheldon might become more in tune with his emotions, and Penny might become more patient. Another theme is the reaction of their friends. Their friends' opinions and reactions often play a big part in the story.
Chapter 595, "Four-legged Black Toad", is the clearest early answer because it turns Zhao Lang's situation into a concrete plot event. The chapter gives readers a real answer by opening on Jiang Li steadied himself with support, endured for a while, and then...
Chapter 426, "How Did Someone Fall Down?!", is the clearest early answer because it turns Xi Yang's situation into a concrete plot event.
Chapter 327, "Official Announcement Entering the Circle!", is the clearest early answer because it pushes Xingmei Entertainment into a new phase or setting.
Chapter 252, "To This Fanatic Fan, Please Calm Down a Bit", is the clearest early answer because it turns Su Yinwan's situation into a concrete plot event.
Chapter 781, "Master, accept my bow!", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Not only were the criminals curious, but so were the others.
Chapter 297, "Is She Really His Granddaughter?!", is the clearest early answer because it turns Grandpa's situation into a concrete plot event. Early on, I was wrong!!!" Before Jiang Li even entered the living room, she....
Chapter 430, "I Quit", is the clearest early answer because it turns Dragon Ridge Island's situation into a concrete plot event. The setup is Hey, do we join a team that's short on members, or do we form our..., but the pressure keeps building through I want to join Team A and follow Ji Yanbai..
Chapter 346, "This person doesn't seem to like her very much", is the clearest early answer because it turns Hua Country's situation into a concrete plot event. The chapter turns that into something concrete by moving from Yes," Jiang Li said, "I learned that this 'Night Walk' is an...
Chapter 513, "A Public Stage", is the clearest early answer because it turns Xiao Shixu's situation into a concrete plot event. It opens with Everyone was sharing their experiences in a few words, the banter... and closes on It's Shiguang's group!" "Performing right after Xi Yang, that's....
Chapter 313, "Grandpa, You Scared My Guest", is the clearest early answer because it turns Shi Xu's situation into a concrete plot event. Early on, When he was brought in, Zhou Wenshu was still in a fog.. By the end, Zhou, hello, I am Jiang Li, it's a pleasure to meet you." Zhou Wenshu....