One TV show that fits your description is "Happy Endings." In the episode titled "The Code War," a character eventually finds out that her husband has been living a secret life, which includes espionage elements and adds a comedic twist to the story. While it’s a comedy, it contains themes related to secrets and espionage.
Another option is "Covert Affairs," which follows a young CIA operative, and while it focuses on her adventures, relationships are also a significant part of the plot, including revelations about personal lives and secrets.
If you are looking for a more dramatic series, "The Americans" deals heavily with espionage and relationships, but it’s often rated TV-MA due to mature content.
Please check your local listings to find out what specific ratings a show might have, as they can vary by network and region.