Honeytrap

At the height of the Cold War, a Soviet and an American agent fall in love.
Soviet agent Gennady Matskevich is thrilled when he's assigned to work with American FBI agent Daniel Hawthorne. There’s just one catch: Gennady’s abusive boss wants him to honeytrap his American partner. Gennady doesn't want to seduce his new American friend for blackmail purposes… but nonetheless, he can’t stop thinking about kissing Daniel.
FBI agent Daniel Hawthorne is delighted to get to know an agent from the mysterious Soviet Union… and determined not to repeat his past mistake of becoming romantically involved with a coworker. But soon, Daniel finds himself falling for Gennady. Can their love survive their countries’ enmity?
Content warning: sexual harassment and assault by a secondary character, period-typical homophobia (probably less homophobia than is strictly historically accurate, but this is a romance novel, not Giovanni's Room), implied/referenced suicide, messy polyamory.