Strangers into Lovers (Harlequin Presents, #454)
Lilian Peake

Randall's words rang in Gillian's head. Their love affair had ended abruptly. Randall West had been dying...and knowing this, Gillian hadn't been able to face him. So she had run away.
Then four years later he walked through the door--alive and well! But it didn't matter, for their lives were on different courses now: Gillian engaged to Everett; Randall engaged to June.
The only thing left between them was Randall's bitterness. Would the grudge he bore her for running out on him ever go away?