Contemporary romance of the1980's /1990's.may or may not be a harlequin

An old harlequin/shilhoutte published maybe in th 80's/ 90's.The hero and heroine meet during a vacation and fall in love.After their night together heroine disappears as she feels guilty(she's already married)FF a few months,the hero goes to visit his father and is shocked to find that the heroine is his stepmother. Cant remember much after that.During the end (the father is dead by now i think)the hero goes to apologise to the heroine and finds her in arms of OM who is a friend of the heroine and is therefore consoling the now pregnant heroine. Seeing the OM protective gesture(has his hands on the heroine abdomen)hero realises its probably too late as the heroine is already pregnant with the OM 's child and returns brokenhearted..That's all I remember🙄

Romance novel where Heroine in a MOC with the hero's father