Passage: "Wonderful Tonight" is a ballad written by Eric Clapton. It was included on Clapton's 1977 album Slowhand. Clapton wrote the song about Pattie Boyd. The female vocal harmonies on the song are provided by Marcella Detroit (then Marcy Levy) and Yvonne Elliman.

Question: Based on this passage, who is eric clapton singing about in wonderful tonight?
Steam of consciousness below:
To answer the above question, the relevant sentence is: Clapton wrote the song about Pattie Boyd.
So, the answer is Pattie Boyd.