Tomas Machac knows how to keep his friends close and his enemies closer. On Friday, Machac and Katerina Siniakova of the Czech Republic defeated China’s Wang Xinyu and Zhang Zhizhen to secure the gold medal in the tennis mixed doubles event at the 2024 Paris Olympics. With a gold medal on the line, the match was already dramatic. However, there was another storyline sneaking beneath most viewers’ noses. Siniakova is Machac’s ex-girlfriend, and possible current girlfriend, while Zhizhen is Machac’s doubles partner outside of the Olympics. Machac’s loyalties were at odds on the court but he ulti…