Assumptions are hard to break

In what looks to be an otherwise solid book for those preparing for marriage, I found a curious explanation of the meaning behind God’s declaration that “it is not good for the man to be alone” (Gen 2:18). In fairness, the author’s presentation falls comfortably within the bounds of popular consensus in spite of the broad assumptions:

Here is my question: in light of all we just said, why is it not good for the man to be alone? What is God seeing and talking about?

The problem that God identifies, and wants us to see, is that Adam has no one of his nature and substance to think about. He has no one in his likeness to love, serve, and honor. Left alone, his thoughts would be too wrapped around himself. This was a problem. This is what God called “not good.” In his alone state, Adam could not reflect the complete image that God wanted him to reflect. He was not as full an image-bearer of God’s glory as God desired.

Two questions. First, where is the support for this interpretation in the text? Second, if this is the problem that God identifies in 2:18, what does this mean for the singles in our midst?

Maybe we assume too much in this verse.