Who is Alice Lee Roosevelt from The Rise of Theodore Roosevelt and what is their importance?

At Harvard, a mutual friend introduces young Theodore Roosevelt to his neighbor's daughter, Alice Lee. Roosevelt immediately falls in love and puts all of his usual passion into gaining her hand in marriage. Though she initially plays coy, they marry soon after Roosevelt gradates from Harvard.

Alice Lee resembles, the author says, a child bride. Beautiful and popular, she and Theodore enjoy a thriving social life. After three years, she becomes pregnant with their first child. Unexpectedly, she falls ill after the girl's birth and never recovers. Her death deals a harsh blow to Roosevelt, who retreats into his work. Eventually, he seeks solace in a solo hunting trip in the west. In accord, apparently, with Theodore Roosevelt's wishes, little evidence survives of Alice Roosevelt.