A Solitary Blue book by Cynthia Voigt

Jeff Greene was only seven when Melody, his mother, left him with his reserved, undemonstrative father, the Professor. So when she reenters his life years later with an invitation to spend the summer with her in Charleston, Jeff is captivated by her free spirit and warmth, and he eagerly looks forward to returning for another visit the following year.

But Jeff's second summer in Charleston ends with a devastating betrayal, and he returns to his father wounded almost beyond bearing. But out of Jeff's pain grows a deepening awareness of the unexpected and complicated ways of love and loss and of family and friendship -- and the strength to understand his father, his mother, and especially himself.