Love is notable in Invisible Man because of its absence throughout most of the novel. The narrator rejects it because it would interfere with his ambitions. At the end of the novel, however, the narrator says he has found love (and its other half, hate), but it doesn't manifest itself as love for any particular person, place, or idea. It's just… nebulous love.
In Invisible Man, love requires the recognition of the true humanity in other people, and, as such, the narrator does not experience love for the bulk of the novel.