Wallace Webb (Andrew Buchan) found out that Helen (Keira Knightley) was cheating on him in Black Doves, but he confusingly didn’t tell his wife that he knew about her affair. By the end of Black Doves season 1, Helen’s double life as a spy had very nearly been outed. Dani (Agnes O’Casey), had told Wallace that his wife was having an affair, and though he denied it at first, he clearly believed her. Even though Wallace was deeply suspicious of Helen’s affair with Jason Davies (Andrew Koji), he didn’t outright confront her about it, and instead pretended like it didn’t even happen.

https://screenrant.com/why-wallace-doesnt-tell-helen-he-knows-about-affair-black-doves/