Full Idea
It is often said that love takes the interests of the lover as being more important than one's own; but here again we would rather say that love takes the lovers interests as its own.
Gist of Idea
Lovers adopt the interests of their beloved, rather than just valuing them
Source
Robert C. Solomon (The Passions [1976], 7.9)
Book Reference
Solomon,Robert C.: 'The Passions (1993 ed)' [Hackett 1993], p.217
A Reaction
This is because he sees emotions as almost entirely self-centred, and almost never altruistic. To me the evolutionary picture suggest a more social view. Many people want the lives of their ex- to go well, without knowing their new interests.