Jaime suspected that it didn't exactly fit within courtly tradition to celebrate one's honeymoon with a sword fight.
Then again, he and Brienne weren't exactly the model of a traditional couple.
The Hand without a Hand and Brienne of Tarth had been wed on the Sapphire Isle with the king in attendance, incandescent shimmers of sunlight reflecting off of the waters that gave the island its name. A political marriage by reputation, a love match in essence, dishonor melding with honor, the Lannister who had slew not one by two monarchs married to the sworn knight and future Evenstar.
The unspoken secret amongst the rulers of Westeros was that this match was the true secret weapon of the newly crowned king, often bewildered and confused by the game he had unexpectedly inherited. Jaime tried to avoid thinking about the implications of this: if he had been granted the hand of the woman he loved as a "punishment", he was more than happy to take it.
The hard work would come later. For now, he had the delights of this moment: the sunshine glaring on their swords, parrying thrust for thrust, back and forth, back and forth, as the devilish gleam in Brienne's eye caught his own.
Show me your darkest side and you better be my bloody match
"Yield!" Brienne demanded as the tip of her sword jolted into his chest, and Jaime's blood sang with heat and desire.
She was still stronger than him.