Showing Brilliant by Ann Roberts

Respected sociology professor Diane Cole has written the book on love. Every matter of the heart is neatly explained, and Diane's life spins in a smooth circle. At her fortieth birthday party a beautiful young stranger named Ronnie Frost surprises her with a kiss, and the predictable story that is Diane's life is complicated further when Ronnie appears in one of her classes.

After Diane agrees to accept Ronnie as her teaching assistant, Diane finds her views on love challenged by her own heart, as she fights the attraction she feels for a woman half her age, a woman who is brilliant in every way.