Science fiction about two astronautes (American and Russian) who go on a space walk or similar. Then the news of a new war between the two nations break out, and one of them leaves his colleague in outer space on the grounds that they are now at war.

[Guillaume]

It was a best seller I think around last year or a few years ago. It was recently translated to French.
I heard about it on a French radio station.
That's all I know.

[Jack]

It's not new but it sounds like

The Kinsman Saga