In London, in 1978

In February 1978, ABBA went to London, where the group attended the British premiere of ABBA - The Movie and made an appearance on a children's television program called Blue Peter, among other events.
During the visit, the band members made some pictures at Dorchester Hotel, as you can see on this post.

Note how both couples seemed to be happy. It really didn't look like Björn and Agnetha were about to split up just two months later.

Benny: "Come on, Frida, gives 'good bye'!"