Is Winterbourne wise to keep his distance between himself and Daisy late in the novel? Or is he foolish because he fails to consider marrying Daisy?

In my opinion, Winterbourne distances himself from Daisy, so as to keep her from humiliating him. Her relationship with another man, in addition to that man's constant presence is a source of embarrassment. Winterbourne believes that Daisy intends to marry Giovanelli... at this point he backs away.