‘Pretending’ is the lead single of Clapton’s album Journeyman.

It is mainly about two characters in a love relationship that drift apart. While he is working late with his band ‘to get the music right’, she is only ‘pretending to understand’ what he is doing. That is why he is ‘satisfied’, but clueless about her real feelings.
When the distance between them becomes apparent, he realizes that he is not ‘who [he] used to think [he was]’.
The last verse (3) is open-ended. It can either refer to his misconception that their love ‘can’t fail’ – when in the end it did just that. Or it could be interpreted as a hopeful note for their relationship, denoting a new beginning, in which ‘sadness cannot prevail’…
Given the rather dark atmosphere of the song and Slowhand’s soulful vocals, I would say that it is likely that the former is true, but I would be more than happy to be convinced otherwise.

The music video features Clapton and his band playing at night in the pouring rain. The idea of rain came from Clapton’s viewing of the Kurosawa films, namely The Seven Samurai.