It's either a 2016 or 2017 movie.
So two secret agents (a woman and a man) were in the War and wanted to kill someone. I think a German.
They were in France.
They fell in love and got married. She gave birth during the war.
At work they told the man that the woman is stealing information from them and send them at Germans.
She confesses and kills herself so they don't kill both of them and the little girl (is still a baby).
At the end it shows us, her writing a letter for her daughter.
This is Allied (2016) with Brad Pitt & Marion Cotillard
In 1942 during World War II, Royal Canadian Air Force intelligence officer Max Vatan travels to Casablanca in Morocco to assassinate the German ambassador. He is partnered with a French Resistance fighter named Marianne Beauséjour, who had escaped from France after her resistance group was compromised and killed.
The two get married, settle down in Hampstead, and have a baby girl named Anna.
A year later, Max learns from the Special Operations Executive that Marianne is suspected of being a German spy, having adopted her identity after the real Marianne was killed in France.
Marianne tells Max that she loves him, asks him to take care of Anna, then shoots herself.
The film ends with Marianne reading the letter that she had earlier written to her daughter, anticipating that one day her real identity would be uncovered.
The name of the movie is probably Allied.
In 1942, a Canadian intelligence officer in North Africa encounters a female French Resistance fighter on a deadly mission behind enemy lines. When they reunite in London, their relationship is tested by the pressures of war.
