One of the many things that Vegeta wasn't fond of was interacting with others. It would often involve small talk, and Vegeta was never good at carrying out a conversation. If a conversation didn't have a purpose, he didn't see why he should participate in it. Luckily for him, most people would notice and eventually stop trying. For them, the room would be filled with awkward silence until they either left or someone else walked in. Vegeta didn't find the silence unbearable. In fact, he preferred it. It gave him time to ponder over things, which was something he did often.
This very fact was one of the many reasons why most people were shocked to discover that Vegeta and Goku were now together. Goku liked talking on and on and on while Vegeta liked staying quiet. However, this seemed to work for the two. It turned out that Vegeta was a great listener, and Goku didn't need him to reply for him to keep talking. Sometimes, Vegeta would be in another one of his moods; during those times, he was not a great listener. Goku eventually learned when it was time for silence, and he respected it.
The two were very different, but it seemed that those differences strengthened each other. Goku would often speak for the both of them when they were at parties so Vegeta wouldn't be forced to engage in conversation he didn't want to be a part of. Vegeta's attentive nature kept their new home organized and clean, and they were never behind on tasks they needed to take care of. He remembered all the important stuff, because Goku tended to forget things easily. Goku knew when it was time to relax when they were training. He was in charge of enforcing those breaks, because Vegeta had a tendency to keep training until he destroyed himself. Vegeta's ruthless nature came in handy when Goku's kind nature made him show mercy to his enemies. Vegeta tended to finish the job when Goku couldn't bring himself to.
It eventually became obvious to others that the two were a good match for the other. This fact had been obvious to Gohan even before the two had realized their feelings for each other. After his father split with his mother on amicable terms, Gohan had noticed Goku was spending more time with Vegeta. Even when they weren't together, Vegeta often became the topic of conversation between him and his father. Gohan noticed Goku would have a certain look on his face when he was talking about the prince, and Gohan realized the reason why long before his father did. For a while, Gohan worried that his father would have his heart broken, because he was certain Vegeta didn't share his feelings. But, one day Gohan had accidentally let it slip that his father would often talk about Vegeta, and he was surprised to see said man's cheeks become flushed.
Even though their feelings were obvious to Gohan, it seemed they were not obvious to the two men. At first, Gohan was determined to not interfere. After all, it wasn't any of his business. But, soon days turned into weeks and weeks turned into months. Gohan feared those months would turn into years and eventually an eternity. He could see his father was happy to just spend time with Vegeta, but he knew his father longed for something more. Videl listened to his concerns, but she told him he should just leave it be. So, he had planned on doing just that.
Then, Gohan received a call from Bulma, telling him that Goku had been injured. He rushed to Capsule Corporation to check on his father and found Vegeta by his bed. His arms were crossed as usual, and everything about his posture came off as cold. Gohan could see through all that with just a look at his face. Concern was not an expression Vegeta often wore. It was reserved for people he cared about. After making sure his father would live, Gohan took Vegeta aside to talk. At first, Vegeta didn't say much, but when he realized that this conversation did have a purpose he spoke more. They talked about many things that day, though most of it revolved around Goku. This was the closest Gohan had ever felt to Vegeta, and he wasn't sure if he could ever get Vegeta to open up to him like this again. The conversation was cut short when he received a text from Bulma saying that Goku had woken up. Before the two went back to the room, Gohan told Vegeta that his father cared about him very much, and that Vegeta should let Goku know how he felt as well.
Gohan was sure that conversation was the catalyst that led to the two men ending up together. He didn't brag about that though. That conversation was a private moment between Gohan and Vegeta that he treasured.
Goku had been happy just being around Vegeta, but he was happier being with Vegeta. Before, Vegeta had always been guarded around everyone. He had walls that were difficult to climb over. For every wall that he manage to climb over, there was another wall with signs telling him to not get too close. Vegeta was fine with letting Goku punch him until his skin turned purple, but he would retreat when Goku wanted to inspect his wounds and care for him. If Goku wasn't hurting him, then he wasn't allowed to touch Vegeta. So, Goku preferred being with Vegeta. He liked not having to climb any walls Vegeta had put up. He liked that Vegeta would allow himself to be vulnerable when it was just the two of them. He liked holding Vegeta as he slept. He liked kissing Vegeta whenever he had the chance. He just liked being with Vegeta.
Before he had come to Earth, Vegeta did not have the luxury to allow himself to relax. Under Frieza's rule, he had to harden his heart in order to survive. He opened up a little when he had been with Bulma, but Goku had been the one to make him realize it was okay to be vulnerable. Though Vegeta was far from being able to express his emotions properly, he knew that Goku understood him. Saiyans didn't care for romance, but Vegeta had to admit he didn't hate that Goku would hold his hand regardless if they were in public or not. He didn't hate it when Goku would hold him when Vegeta was feeling upset. He didn't hate the way Goku would pull him close so he could kiss him. He didn't hate it when Goku would lean in and whisper in his ear that he loved him. He just didn't hate being with Goku.
They just loved being with each other.