What was the English movie where both friends have affair with their friend?

It's difficult to give you a definitive answer without more information. There are many movies where friends have affairs, and it's possible you're thinking of a film with a specific plot twist or theme.

To help me narrow it down, could you provide some more details about the movie you're looking for? For example:

* What is the approximate year of release?

* What is the genre of the film? (e.g., comedy, drama, thriller)

* Do you remember any of the actors?

* What is the overall tone of the movie? (e.g., lighthearted, serious, scandalous)

The more details you can provide, the better chance I have of identifying the film you're looking for.