The Doctor's Wife by Elizabeth Brundage

Busy Dr. Michael Knowles doesn't have enough time for his family, yet he takes on yet one more job moonlighting at a women's health clinic. His wife Annie's role as mother/teacher is becoming stale. She begins a love affair with notorious painter Simon Haas, who is married to Lydia, who has problems of her own. Thus begins a tale of intrigue, suspense, and cheating spouses. The author keeps the reader entertained to the very end. Sandy Penton