"I look like the Flash about to get married."
The two major storylines that have revolved around Howard are his relationship with Bernadette, and him becoming an astronaut. In this episode, once again, these two storylines entwine themselves together, but in an unlikely manner. After Howard received a call indicating that the space mission was cancelled due to technical difficulties, Howard was relieved, as he was afraid of going into space. But when he was later told that he could go on the next flight, he noticed that the time frame also coincided with the wedding. Howard tried to get out of space mission without admitting his fear, by getting Bernadette's father to side with him on the wedding date. However, Bernadette's father proved to be too supportive of the space mission to delay the wedding.
The topic of marriage also came up between Penny and Leonard. In typical Leonard fashion, he blurted out the wrong thing at the wrong time. This triggered the now standard surpised (but should not be) reaction from Penny, followed by Leonard apologizing profusely, and saying dumb things to try to make things better.
While things between Penny and Leonard hit yet another speed bump, Amy and Sheldon were moving forward. So far, Amy's intentions with Sheldon in this relationship have not resulted in what she had hoped for. Unlike Sheldon, Amy wants more than just an intellectual relationship. She wants an actual real relationship. In order to do so, Amy used her genius brain to her full capacity to meet all of Sheldon's needs, with the intention of creating an emotional attachment. It was carefully planned, and even spelled out to Sheldon. This was Amy's plan to make Sheldon reciprocate the feelings she had for him. And it worked.